Medical glossary Prepared by: Dr. Mohammed Alruby Medical glossary Aberrancy: occurring or developing away from the normal situation Acantholysis: loss of coherence between epithelial cells due to degeneration of desmosomes (intercellular bridge) this will lead to the formation of intra-epithelial clefts, vesicle and bullae Acanthosis: epithelial hyperplasia, mainly of the stratum spinosum, leading to increase thickness of the stratum granulosum due to increased number of cell layers of prickle cells Achondroplasia: an autosomally inherited disorder characterized by abnormality of conversion cartilage into bone predominantly affecting the epiphyses of long bones, leading to retarded growth at the epiphyses and resulting in dwarfism with short extremities but normal trunk Acidogenic: referring to organisms capable of producing acid Aciduric: referring to organisms capable of surviving and metabolizing under highly acidic conditions Acquired: a term used to describe a condition, habit or other characteristic which is not present at birth, which developed in the individuals by reaction to some environmental factor (to acquire is to obtain) Agenesis: failure of formation leading to absence of a part or organ Aglossia: failure of formation leading to absence of the tongue Agnathia: absence of the jaw, usually the lower jaw, usually accompanied by approximation of the ears Amyloid: pertaining of starch, having the characteristic of starch. A protein compound of albumin and chondroitin sulphate which resembles starch in appearance and may be pathologically deposited in certain tissues Anaplasia: atypical differentiation or lack of differentiation of epithelial cells occurring in the malignant disease. Anaplastic cells have large, hyperchromatic, irregularly shaped nuclei and frequently show a typical mitosis. Aneuploidy: an abnormal number of chromosomes in a nucleus. This usually arise from failure of paired chromosomes or sister chromatids to disjoin at anaphase of cell division Aneurysm: circumscribed dilatation of an artery Aneurysmal: relating to an aneurysm. The term applied to a type of cyst that produce bony expansion simulating the expansion of an artery produced by a vascular aneurysm Angiogenesis: development of blood vessels Angioma: a swelling or mass due to proliferation with or without dilatation of vascular channels Anhydrosis: absence of sweating due to absence of sweat glands Ankyloglossia: tongue tie, usually due to a short lingual frenum or one attached too near the tip of the tongue, may be due to failure of separation of tongue from the floor of the mouth during embryogenesis Ankylosis: stiffening or fixation of a joint as a result of a disease process Anodontia: absence of teeth Anomaly: deviation from the normal, anything structurally unusual or irregular Antigen: a substance that can induce an antibody response Antimongoloid slant: an obliquity of the palpebral fissures laterally

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Dr. Mohammed Alruby
Medical glossary
Prepared by:
Dr. Mohammed Alruby
Medical glossary

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Dr. Mohammed Alruby
Aberrancy: occurring or developing away from the normal situation
Acantholysis: loss of coherence between epithelial cells due to degeneration of desmosomes
(intercellular bridge) this will lead to the formation of intra-epithelial clefts, vesicle and bullae
Acanthosis: epithelial hyperplasia, mainly of the stratum spinosum, leading to increase thickness
of the stratum granulosum due to increased number of cell layers of prickle cells
Achondroplasia: an autosomally inherited disorder characterized by abnormality of conversion
cartilage into bone predominantly affecting the epiphyses of long bones, leading to retarded
growth at the epiphyses and resulting in dwarfism with short extremities but normal trunk
Acidogenic: referring to organisms capable of producing acid
Aciduric: referring to organisms capable of surviving and metabolizing under highly acidic
conditions
Acquired: a term used to describe a condition, habit or other characteristic which is not present
at birth, which developed in the individuals by reaction to some environmental factor (to acquire
is to obtain)
Agenesis: failure of formation leading to absence of a part or organ
Aglossia: failure of formation leading to absence of the tongue
Agnathia: absence of the jaw, usually the lower jaw, usually accompanied by approximation of
the ears
Amyloid: pertaining of starch, having the characteristic of starch. A protein compound of albumin
and chondroitin sulphate which resembles starch in appearance and may be pathologically
deposited in certain tissues
Anaplasia: atypical differentiation or lack of differentiation of epithelial cells occurring in the
malignant disease. Anaplastic cells have large, hyperchromatic, irregularly shaped nuclei and
frequently show a typical mitosis.
Aneuploidy: an abnormal number of chromosomes in a nucleus. This usually arise from failure of
paired chromosomes or sister chromatids to disjoin at anaphase of cell division
Aneurysm: circumscribed dilatation of an artery
Aneurysmal: relating to an aneurysm. The term applied to a type of cyst that produce bony
expansion simulating the expansion of an artery produced by a vascular aneurysm
Angiogenesis: development of blood vessels
Angioma: a swelling or mass due to proliferation with or without dilatation of vascular channels
Anhydrosis: absence of sweating due to absence of sweat glands
Ankyloglossia: tongue tie, usually due to a short lingual frenum or one attached too near the tip
of the tongue, may be due to failure of separation of tongue from the floor of the mouth during
embryogenesis
Ankylosis: stiffening or fixation of a joint as a result of a disease process
Anodontia: absence of teeth
Anomaly: deviation from the normal, anything structurally unusual or irregular
Antigen: a substance that can induce an antibody response
Antimongoloid slant: an obliquity of the palpebral fissures laterally downwards in contrast to the
laterally upward slant seen in mongoloid races
Aplasia: congenital absence of an organ or tissue. in heamatology, incomplete, retarded or
defective development, or cessation of the usual regeneration process
Apoptosis: cell deflection by fragmentation into membrane-bonded particles which are
phagocytosed by other cells
Apostematosa: apostema, old name of abscess, cheilitis glandularis Apostematosa means chronic
inflammation of the lower lips with swelling of mucous gland, ulceration and small abscess

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Dr. Mohammed Alruby
Atresia: absence of a normal opening or normally patent lumen
Atrophy: wasting of tissue, organs, or the entire body resulting from death and reabsorption of
cells, diminished cellular proliferation, pressure, ischemia malnutrition decreased function or
hormonal or hormonal changes.
Atypsia: a state of being not typical, not conforming to the normal structure of the part
Autoradiography: the process of producing an autoradiograph, which is a reproduction of the
distribution and concentration of radioactivity in a tissue, made by placing a photographic
emulsion in close proximity to the part
Autosomal: a trait transmitted by a gene carried on an autosome (any member of the 22 paired
chromosomes other than the X and Y sex chromosome)
Ballooning degeneration: a type of degeneration of epithelial cells causing marked swelling with
loss of intercellular bridges, Acantholysis results and vesicle or bulla is formed.
Benign: denoting the mild character of an illness, or the nonmalignant nature of neoplasm.
Bleb: a large flaccid vesicle
Boss: a circumscribed rounded swelling or prominence
Bosselated: marked by numerous bosses or rounded protuberances
Botryoid: having numerous rounded protuberances resembling a bunch of grapes
Buccal: pertaining to or adjacent to, or in direction of cheek
Bulla: a large vesicle from 5mm to several centimeters in size
Cachexia: a general lack of nutrition and wasting occurring in the course of a chronic disease or
emotional disturbance
Calculus: stone, a concretion formed in any part of the body, mostly biliary, urinary or salivary
passages and formed of inorganic or organic salts
Cariogenic: capable of producing caries
Cell nest: a term used to describe a cluster of cells arranged in a concentric manner like a bird’s
nest usually found in malignant neoplasm of the skin or mucous membrane
Cellular adhesion: attachment of cells to neighboring cells through desmosomes and various type
of cell junctions
Cellular pleomorphism: variation in the size, shape, and staining of cells of the same tissue or
neoplasm
Cellular polarity: the direction or orientation of cells in a common direction, this is lost if cells
lose their adhesion to neighboring ones
Centromere: the constriction of a chromosome which is the point of attachment of the spindle fiber
and is concerned with chromosome movement during cell division
Cheilitis: inflammation of lips, angular cheilitis denotes inflammation of lips with redness and the
production of fissures radiating from the corner of the mouth
Chemotaxis: attraction of living cells or protoplasm to chemical stimuli
Cherubism: a form of fibro- osseous lesion of the jaws producing the characteristic facies of the
cherub
Coloboma: the part taken away from mutilation, denoting any defect, congenital, pathologic or
artificial, especially of eye (of palpebral fissure). A congenital notch in the eyelid margin
Congenital: existing since before birth or at birth, dating from birth, congenital malformations are
anatomical or structural abnormalities that are present at birth, though they may not be diagnosed
until later.
Craniotabes: a disease marked by the presence of areas of thinning and softening in the bones of
the skull

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Dr. Mohammed Alruby
Cyst: an abnormal sac (cavity) containing gas, fluid or a semisolid material, with a membranous
epithelial lining
Deaf-mutism: in ability to speak due to congenital or early acquired profound deafness
Deletion: (genetic): loss of a portion of chromosome between two break points or as a result of a
parental translocation
Dense in dent: a developmental disturbance in tooth formation resulting from invagination of
odontogenic epithelium associated with enamel development into the area which was supposed to
be the pulp space, after calcification, there is an invagination of enamel and dentine into the pulp
space, and distortion of pulp space and the root contour to accommodate this invagination
Dense: tooth, a tooth like process
Dantigerous: arising from or associated with teeth
Dentinoid: resembling dentine
Desmoplastic: causing fibrosis in the stroma of neoplasm
Desmosome: site of adhesion between two cells, consisting of a dense plate separated from similar
structure in the other by thin layer of extracellular material
Developmental: characterized by, or belonging to the process of development
Dextran: approved name for ploy-an-hydro-glucose. It is a gummy high molecular weight glucose
polymer produced by the action of certain bacteria on carbohydrates
Diabetes insipidus: chronic excretion of very large amount of pale urine of low specific gravity,
accompanied by extreme thirst, usually resulting from inadequate production of pituitary
antidiuretic hormone
Dichotomy: cutting or division into two parts
Dilaceration: displacement of some portion of a developing tooth which is then further developed
in a new direction resulting in a tooth with sharply angulated root
Dizygotic: twins derived from two different zygotes
Dominant: a dominant gene is which will produce its effects when present in either heterozygous
or homozygous condition (when only one or both alleles are affected)
dyskeratosis: imperfect or abnormal development, orientation and keratinization of epithelial
cells. The appearance of premature keratinization in individual cells that have not reached the
keratinizing surface layer. Keratinization of individual cells or groups of cells may occur within
the lesions; the cells exhibit hyper-chromatism, loss polarity and increased nuclear size and
prominent nucleoli, and there may also be an increased mitotic rate with abnormal mitosis
Dysostosis: defective bone formation
Dysplasia: abnormal tissue development
Dystrophy: defective nutrition
Ectopic: aberrant, out of place, refers to an organ or structure which is not in its proper position
Enucleation: the entire removal of a tumor, a cyst or other structure in one piece without rupture
Epiphora: an overflow of tears upon the cheek due to imperfect drainage by the lachrymal duct
Epithelial pearl: whorls of epithelial cells arranged in a concentric manner, with keratin in its
center
Erosion: a shallow defect in the surface mucosa representing loss of epithelium down to, but not
including, the basal layer
Erythroplakia: a red, velvety plaque-like lesion of mucous membrane which often represents
developing malignant change
Exanthema: a skin eruption occurring as a symptom of an acute viral or coccal disease

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Dr. Mohammed Alruby
Exophthalmos: prominence or protrusion of the eyeballs due to disease to such an extent that the
eyelids will not cover them
Expressivity: the degree to which effects of a gene are expressed or shown in an individual
Familial: affecting several members of the same family
Fistula: an abnormal passage from a hollow organ to the surface or from one organ to another
Fluorosis: a condition caused by an excessive intake of fluorides
Foam cells: cells with abundant, pal-staining, finely vacuolated cytoplasm, usually histocytes that
have ingested or accumulated material that dissolves during tissue preparation, usually lipid
Fontanelles: un-ossified, membranous intervals at the angles where the parietal bone meet other
bones in the infant.
= The anterior fontanelle is a diamond- shaped interval closed by membrane at the junction of the
frontal, coronal, and sagittal sutures. It is normally ossified at about twelve months of age
= the anterior lateral fontanelle is an interval at the junction of the parietal bone with the fontal,
squamous, temporal and greater wing of the sphenoid bone, it is normally obliterated within the
1st
three months after birth.
= the posterior fontanelle, is a triangular interval at the junction of the sagittal and lambdoid
sutures. It is normally ossified within the 1st
three months after birth.
= the posterior lateral fontanelle is an interval between the adjacent edges of the parietal, occipital
and temporal bones. It is normally closed by eighteen months of age
Fusion: the growth together, as one of two or more teeth, in consequence of abnormal union of
their formative organs
Germination: embryonic partial division of primordium as, of a tooth germ resulting in two
partially or completely separated crowns
Genetic: transmitted from one generation to another through genes, same as hereditary
Ghost cell: a dead cell in which the outline remains visible, but without other cytoplasmic
structures or stainable nucleus. Ghost cells may become keratinized and may classify
Glossoptosis: falling back of the tongue
Gnotobiote: an originally germ-free animal that has been inoculated with known and controlled
bacteria
Hemangioma: a swelling or tumor due to proliferation, with or without dilatation, of blood vessels
Hamartoma: a focal malformation, resulting from faulty development of an organ or tissue that
resemble neoplasm
Hepatomegaly: enlargement of liver
Hereditary: transmitted from ancestors or parents to a child, same as genetic
Heredity: the transmission of character from parents to offspring
Hyaline: having glossy, homogenous, translucent appearance
Hydropic degeneration: this signifies edema and degeneration of basal cells; the nuclei being
replaced by clear spaces. The entire basal cells gradually degenerate and the epithelial connective
tissue boundary becomes ill-defined
Hyper-chromatic (nuclei): abnormally highly colored, excessively stained nuclei
Hyperkeratosis: this means widening or thickening of the stratum corneum. It results clinically in
a white lesion. The degree of whiteness and opacity of the lesion is related to the degree of
hyperkeratosis.
Hyper-parakeratosis: increased thickness of keratin layer with retained pyknotic nuclei

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Dr. Mohammed Alruby
Hyperplasia: increase of size of a tissue or organ due to increase in the number of its constituent
cells. Hyperplasia of connective tissue is characterized by a markedly increased density of collagen
fibers
Hypertrophy: increased size of a tissue or organ due to increase in size of its constituent cells
Hyperhidrosis: diminished sweating
Hypoplasia: underdevelopment of a tissue or organ due to decrease in number of its cells
Inversion: this arises through two chromosomal breaks with inversion through 180 degree of the
segment between the breaks
Karyolysis: apparent destruction of the nucleus of a cell with loss of affinity of its chromatin to
basic dyes
Karyorrhexis: a state of necrosis characterized by fragmentation of the nucleus whereby its
chromatin is irregularly distributed in the cytoplasm
Leukoedema: a benign abnormality of the oral mucosa clinically resembling leukoplakia,
consisting of filmy, opalescent to whitish-gray finely to a coarsely wrinkled epithelium
Leukoplakia: a disturbance of keratinization of mucous membranes. Variously present as
opalescent patches or as extensive leathery plaque, occasionally ulcerated, histologically it may
exhibit disturbance in the orderly maturation of stratified squamous epithelium and is then
regarded as precancerous
Levan: a polymer of fructose produced by action of certain bacteria on sucrose
Lymphangioma: a swelling or tumor due to proliferation with or without dilatation of lymphatic
vessels
Macrodontia: abnormally large teeth
Macroglossia: enlargement of tongue
Macrognathia: enlargement or elongation of the jaw
Macrostomia: abnormally large mouth
Macule: a circumscribed non-raised area of altered coloration varying in size from a pinhead to
several centimeter is diameter. Macules may be circular, ovoid, or linear, there color is usually
deeper the surrounding normal mucosa, and they may be red, brownish –red or brown-black.
= A macular eruption may represent punctate hemorrhage as seen in thrombocytopenic purpura,
it may contain melanin deposits as in Addison’s disease or it may consist of small vascular
malformation as in hereditary telangiectasis.
Malignant: in reference to a neoplasm, having the property of local invasiveness, destructive
growth and metastasis
Melanoblast: a cell derived from the neural crest, it migrates to various parts of the body during
early embryogenesis and then becomes a mature melanocyte
Melanocyte: a cell located at the dermal epidermal junction, having dendritic processes and
capable of forming melanin
Melanophore: a phagocytic cell that contain melanin but does not form the pigment
Mendelian: attributed to or described by Mendel
Mesiodens: a supernumerary tooth located in the midline of the upper jaw
Metaplasia: abnormal transformation of an adult, fully differentiated tissue of one kind into a
differentiated tissue of another kind
Microdontia: single or multiple disproportionately small teeth
Microglossia: smallness of the tongue

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Dr. Mohammed Alruby
Micrognathia: smallness of the jaws, especially lower jaw
Microradiography: making a radiograph of a uniform thickness ground section
Microstomia: smallness of the mouth
Monostotic: occurring in single bone
Monozygotic: twins: twins resulting from a division into two of an embryo derived from a single
fertilized ovum, such twins are genetically identical
Mosaic pattern: a tessellated pattern resembling inlaid work
Mosaic: an individual with cell lines, or tissue of different chromosomal constitution
Mottling: an area comprised of varying shades or colors
Multi-locular: many celled having many compartments
Multiple: occurring in several parts at the same time
Nevus: a circumscribed malformation of the skin or mucous membrane, consisting of cells native
to the part and grossly resembling to a neoplasm
Necrosis: this means destruction of the epithelium and its replacement by an amorphous mass of
tissue. it is usually brought about by chemicals or by some bacterial products as in fusospirochetal
disease ( progressive painful infection with ulceration, swelling and sloughing off of
dead tissue from the mouth and throat due to the spread of infection from the gums).
Neoplasia: the pathologic process that results in the formation of neoplasm.
Neoplasm: an abnormal growth due to more rapid cellular proliferation than normal and that
continues to grow after cessation of the stimuli that may have evoked it
Neuralgia: pain of a severe throbbing or stabbing character in the course of distribution of a
sensory nerve
Non-disjunction: failure of two homologous chromosomes to separate and pass into two separate
gametes (or cells) either at meiosis or mitosis.
Nuclear pleomorphism: variation in size and staining of nuclei, resulting from unequal content of
chromatin, usually seen in malignant neoplasms
Ocular: ophthalmic, pertaining to eyes
Odontome: a tooth like structure with abnormal arrangement of the component tissues
Oophoritis: inflammation of the ovary
Operon: a genetic functional unit that controls production of a messenger RNA, it consists of an
operator gene and two or more structural gene located in sequence in one chromosome
Orchitis: inflammation of testis may be associated with mumps
Osmosis: the phenomenon in which water or other solvent or solutes pass through a membrane
Osteogensis imperfecta: a condition of abnormal fragility and plasticity of bones with recurring
fractures on minimal trauma
Osteomalacia: a disease characterized by gradual softening and bending of bones with varying
degrees of severity of pain
Osteopetrosis: a disease characterized by extensive formation of dense trabecular bone and
calcified cartilage, leading to obliteration of marrow spaces and narrowing of foramina
Oxycephaly: a type of craniosynostosis in which there is premature closure of the lambdoid and
coronal sutures resulting in an abnormally high, peaked or conically shaped skull
Papilla: a small elevation shaped like a nipple
Papilleferous: bearing papillae
Papule: a small circumscribed solid elevated area varying in size from a pinched to about 5mm.
Its base may be round or ovoid and the surface configuration may be pointed, rounded, or flattened

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Dr. Mohammed Alruby
A popular eruption on the oral mucosa usually consists of large numbers of individual pinhead
lesions arranged in varying patterns
The color of individual papules on the oral mucosa is usually greyish white and gross lesions
composed of numbers of papules may be white as: lichen planus
Paranesthesia: an abnormal sensation such as burning, pricking or tingling sensations
Parakeratosis: here there is persistence of nuclei in the stratum corneum. In the parakeratosis the
stratum corneum presents varying degrees of thickening so that it may be actually be
hyperkeratotic
Parakeratosis usually results clinically in a white lesion
Pedunculated: a growth attached to the normal surface by a pedicle or stalk
Penetrance: frequency with which a genetic effect is shown in a population
Plaque: small, or large, raised or depressed firm clearly demarcated area of greyish or white
coloration.
Its surface may be relatively smooth or it may be rough and pebbled in texture. Cracks or fissures
may appear on its surface. Multiple, closely placed papules may resemble a plaque superficially,
but close examination with a magnifying glass will reveal the nature of the lesion
Pleomorphic: having more than one form
Polarized light: light whose waves
Polyostotic: involved more than one bone
Polyp: a tumor with a stalk
Polyposis: the presence of several polyps
Precocity: unusually early or rapid development of mental, sexual or physical characteristic
Premalignant: a lesion from which a malignant neoplasm may be develop in a significant number
of cases
Prenatal: occurring before birth
Primordial: primitive: relating to the structure in its first or earliest stage of development
Primordium: an aggregation of cells in the embryo indicating the first trace of a developing organ
or structure
Prognathism: abnormal projection of one or both jaws
Pseudo-epitheliomatous hyperplasia: is characterized by:
- Extensive down growth of rete pegs accompanied by marked acanthosis giving rise to an
appearance similar to that of carcinoma
- Cells are normal in size and shape and are not hyperchromatic
Ptosis: a sinking down or dropping of an organ. Dropping of upper eyelid
Pustule: is a vesicular type lesion containing purulent material instead of clear fluid
Pyknosis: condensation or reduction in size of a cell or its nucleus
Radiolucent: neither wholly penetrable nor wholly impenetrable by x-ray or other forms of
radiation
Radiopaque: exhibiting opacity to, or relative impenetrability by x-ray or other forms of radiation
Recessive: a recessive gene is one which will produce its effects only when present in a homozygous
condition (only when both alleles are affected)
Refined carbohydrates: carbohydrates from which the fiber content has been extracted resulting
in concentration and availability of its sugar content
Refractive index: the degree of refraction of a ray of light when passing from one medium to
another
Rickets: a vitamin D deficiency disease characterized by over production and deficient
calcification of osteoid tissue

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Dr. Mohammed Alruby
Sarcoidosis: a systemic granulomatous disease of unknown cause especially involving the lungs
with resulting fibrosis, but also involving lymph nodes, skin, liver, spleen, eyes, and parotid glands.
The granulomas are composed of epithelioid and giant cells with little or no necrosis
Sessile: a tumor attached to the surface directly by a broad base without a pedicle or stalk.
Having a broad base of attachment.
Sex linked: a trait transmitted by a gene carried on one of the sex chromosome
Sinus: a channel for the passage of blood or lymph. A hollow in bone or other tissue. a tract
leading from a suppurating cavity to a skin or mucosal surface
Solitary: single
Splenomegaly: enlargement of spleen
Spongiosis: this signifies intercellular edema of the epithelium. The intercellular bridges of the
stratum spinosum become more prominent
Supernumerary: more than the normal number
Supplemental: (teeth) supernumerary resembling those of the normal dentition in area of their
occurrence
Teratogen: any agent that can induce or increase the incidence of the congenital malformation.
An agent capable of causing abnormal development prior to birth
Teratogenic: capable of producing a developmental malformation in the embryo
Tract: an elongated area or path
Trait: a characteristic, especially one that distinguish an individual from others
Translocation: transfer of chromosomal material between chromosomes. This involves breakage
of both chromosomes with repair in an abnormal arrangement
Tumor: any swelling or tumefaction. One or the signs of inflammation. Used as synonymous with
neoplasm
Ulcer: is a defect or breakage in continuity of surface epithelium reaching and involving the corium
It results in a depression or a punched-out area. The floor of an ulcer is formed of connective
tissue and fibrin, and may be contain a polymorph nuclear leukocytic infiltrate.
An ulcer may small about 2mm or quite large reaching several centimeters in diameter.
Unilocular: having only one compartment or cavity
Verrucous: resembling a wart, denoting wart like elevations
Vesicle: a small 2 to 5mm cavity forming either within or underneath the epithelium and filled with
fluid. It gives rise to a circumscribed, elevated lesion composed of a thin surface covering overlying
and containing an accumulation of fluid
X-linked: a trait whose gene is located on an X chromosome
Xanthoma: a yellow nodule or plaque, specially of the skin or mucous membrane, consisting of
lipid –laden histocyte
Xerostomia: dryness of the mouth