Medical Terms - Dissected,  Defined And Explained

Compiled and written by Charlotte Edwards, UCL, Aug 2004  ©

Medical (especially anatomical) terms are daunting at first.  They can seem almost like a different language.  It is important not to panic.  Don’t attempt to memorise lists of words.  Terms will soon become familiar once you start using them in the dissection room.  The most useful approach is to understand the derivation of key words.  Often their component parts come up time and time again, within unfamiliar words.  By learning the meaning of these, you can often work out what a new word means - or see where it came from.

This glossary should help transform rote learning into something far more productive.  It is by no means exhaustive, but the derivations are relevant in many subject areas.  Students already familiar with Latin and/or Greek will have a head start.  A short glossary of  Physiology and Related Sciences is also available.

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A- = prefix denoting without
Agammaglobulinaemic = blood (haem) lacks gammaglobulin
Apnoea = cessation of breathing
(N.B. see also ad- and an-)

Ab = away from (Latin)
Abduction = movement of limb away from the midline of the body.
Abembryonic = away from or opposite the embryo

Ad = towards, beside (Latin)
Adduction = movement of limb towards the midline of the body.
Adaxial = towards the main axis
N.B. often becomes a- followed by a double letter as in the following
Affect (verb) = do something to something (Contrast effect: see under E- )
Agglutination = particles sticking to each other

-aemia = suffix denoting a specified bio-chemical condition of the blood
Hyperglycaemia = excess sugar in the blood
Anaemia = reduction in the amount of haemoglobin in the blood

An- = prefix denoting without, lacking
Anaerobe = an organism that is able to live and grow in the absence of free oxygen
Anaesthesia = loss of feeling or sensation in a part or all of the body
(N.B. in some cases the same meaning of ‘without’ can be conveyed by the ‘A’- alone as the prefix)

Angio- = prefix denoting blood or lymph vessels
Angina pectoris = pain in the centre of the chest occurring when the demand for blood by the heart exceeds the supply of the coronary arteries
Angiogenesis = the formation of new blood vessels

Ante = before (Latin)
Anterior = near or nearer to the front.
Antenatal = before birth
(N.B. do not confuse with Anti- = opposite, against)
Anti- = opposite, against
Antidromic = describes impulses travelling the wrong way in a nerve fibre
Anticoagulant = a drug that prevents the clotting of blood
(N.B. do not confuse with Ante- = before)
-ase = suffix denoting enzyme that breaks down a substance
Lactase = enzyme that breaks down lactose into glucose and galactose
Dehydrogenase = enzyme that catalyses an oxidation reaction

Arthr(o)- = relating to joints [Grk]

Aural = relating to the ear (auricula = ear, Latin)
Auriscope = apparatus used to examine the eardrum and passage leading to it
(N.B. do not confuse with oral = relating to the mouth)

Bi = two
Bicuspid = having two cusps e.g. the mitral valve of the heart
Biceps = a muscle with two heads

Brachi- = related to the arm
Brachial artery = artery in the arm running from the armpit to the elbow
Brachialgia = pain in the arm

Brady- = prefix denoting slowness
Bradycardia = slowing of heart rate to less than 50 beats per minute
Bradylalia = abnormally slow speech

Broncho- = prefix denoting bronchial tree
Bronchitis = inflammation of the bronchi
Bronchospasm = narrowing of bronchi by muscular contraction in response to some stimulus

Calc- = relating to calcium (Latin)
Hypercalcaemia = high blood calcium
Hypocalcaemia = low blood calcium

Cardi- = prefix denoting the heart
Cardiomegaly = enlargement of the heart
Cardiac muscle = muscle of the heart wall

Cephal- = prefix denoting the head
Cephalocele = neural tube defect
Cephalalgia = pain in the head
Corona = crown (Latin)
Corona capitis = crown of head
Coronal plane = divides the body into dorsal (back) and ventral (front) parts

Costa = rib (Latin)
Costal groove = groove on the undersurface of each typical rib behind which intercostal nerves and vessels run
Intercostals = muscles running between the ribs

Cyst = an abnormal sac or closed cavity lined with epithelium and filed with liquid or semisolid matter
Cyst- = prefix denoting a bladder esp. the urinary bladder
Cystitis = inflammation of the urinary bladder, often caused by infection
Cystalgia = pain in the urinary bladder

Cyto- = prefix denoting cell or cytoplasm
-cyte = suffix denoting cell or cytoplasm
Cytokinesis = division of the cytoplasm of the cell
Chondrocyte = a cartilage cell

Di- = prefix denoting two (Latin)
Dipeptide = compound consisting of two amino acids joined together by a peptide bond
Disaccharide =carbohydrate consisting of two linked monosaccharide units
.. beware confusion with dis-

Dia- = through, throughout
Dialysis = method of separating particles of different dimensions in a liquid mixture, using a thin semi-permeable membrane
Diarrhoea = frequent bowel evacuations or the passage of abnormally soft faeces

Dis- = reversed or separated
Dislocation = separation of bones in a joint
Disinfection = removal of infection
..easily confused with di- meaning two (e.g. disulphide) or dys- meaning abnormal (e.g. dysfunction)

Distal = situated away from the origin or point of attachment or from median line of the body

Dors- = prefix denoting the back (from dorsum, Latin)
Dorsal = situated close to the back of body or the posterior of an organ
Dorsoventral = extending from back to front surface

Dys- = abnormal, painful
Dyspnoea = shortness of breath
Dysgenesis = faulty development

E-  (see also Ex-)  = out of, outside, from
Evaginate = protrude outside a covering
Effect (noun) = outcome, arising from something: Drugs often have both good and bad effects.
Effect (verb) = have as an outcome: Drugs can effect cures.
Distinguish carefully from
Affect (verb) = do something to:  Effective pain-killers may affect the patient's alertness.

-ectomy = cutting and removing
Lobectomy = removing a lobe of an organ
Appendicectomy = removal of the appendix

Endo = within
Endogenous = arising within a tissue
Endoderm = inner of the three germ layers of the early embryo

Epi = above, surrounding
Epidermis = outer parts of skin
Epicardium = layer of tissue immediately surrounding the heart (part of pericardium), the outermost layer of the heart wall.

Eu = normal
Eupnoea = normal breathing
Eupepsia = state of normal or good digestion

Erythr- = prefix denoting redness
Erythrocyte = red blood cell
Erythema = redness, rubor – a flushing of the skin due to dilation of the blood capillaries in the dermis

Ex = out of, from (Latin)
Extension = opposite of flexion.  The movement of a joint, in the sagittal plane, making the angle between bones greater. E.g. kicking a ball, extends the knee.
N.B. Often becomes just e-, sometimes  followed by a double letter e.g.:
Effusion = escape of a fluid (e.g. blood) from tissue.

Exo = outside
Exogenous = something not usually found within tissue.
Expiration = the act of breathing out from lungs

Extra = outside (Latin)
Extrapleural = relating to tissues of chest wall outside the parietal pleura.
Extraembryonic coelom = the cavity, lined with mesoderm that surrounds the embryo from the earliest stages of development.

Fer- = carry (from fero = I carry, Latin)
Afferent = carry into e.g. an afferent blood vessel feeds a capillary network in an organ
Efferent = carry from e.g. designated vessels that drain fluid from an organ
Transfer = carry across
(N.B. do not confuse with ferr- = prefix relating to iron
ferritin = iron/ protein complex stored in tissue
ferrous compounds = compounds of  iron where the iron is in its +2 oxidation state
ferric compounds = compounds of iron where iron is in its +3 oxidation state)

Fissure = a groove or cleft (from fissilis = split, Latin)
Oblique fissure = divides lung into lobes and runs around the lung
Horizontal fissure = divides right lung into 3 lobes and extends laterally to meet the oblique fissure.
Flex- = bend (from flexus, Latin)
Flexion = movement of joint in the sagittal plane, usually making the angle between bones less e.g. bringing fist towards shoulder.
Lateral flexion (usually of the spine) = bending to the side

Fossa = a depression or hollow, (literal translation = ditch, trench, Latin)
Iliac fossa = the depression in the inner surface of the ileum
Fossa ovalis = depression on wall of the right atrium that separates the right atrium from the left. It represents the septum primum of the developing heart.

-genic = giving rise to (Latin)
-genous = arising from (Latin)
exogenous = something that comes from outside the body

Glomerulus (Latin) A small ball like structure as in kidney glomeruli, synaptic glomeruli

Haemo-, haem-, haemato-, -aem- (US hemo- etc.) = relating to blood
haemostasis = arrest of bleeding
haematocrit = fraction of blood volume occupied by red cells

Hemi- = prefix that in medicine denotes the right or left half of the body
Hemianaesthesia = anaesthesia of one side of the body
Hemicolectomy = surgical removal of about half of the colon (large intestine)

Hepat- = prefix denoting the liver
Hepatic artery = artery that supplies the liver
Hepatic flexure = the bend in the colon underneath the liver where the ascending colon joins the transverse colon.

Hetero = different, varied
Heterozygous = describes an individual in whom the pairs of genes determining a particular characteristic are dissimilar
Heterotopia = displacement of an organ or part of body from its normal position.

Histo- = prefix denoting tissue
Histology = study of the structure of tissues by means of staining techniques combined with light and electron microscopy
Histogenesis = the formation of tissues

Homo = the same
Homogeneous, homogenous = having uniform properties
Homologous = describing organs or parts that have the same basic structure and evolutionary origin, but not necessarily the same function or superficial structure.

Hydr- = prefix denoting water or a watery fluid (Latin)
Hydrocele = accumulation of watery liquid in a sac.
Hydrocephalus = an abnormal increase in the amount of cerebrospinal fluid within the ventricles of the brain

Hyper = above normal
Hyperventilate = breathing more than normal
Hyperglycaemia = an excess of blood glucose in the blood stream.

Hypo = below, less than normal
Hypodermic = below the skin
Hypotension = condition in which the arterial blood pressure is abnormally low

In vitro = literally translated as ‘in glass’. Usually refers to a procedure carried out isolated from body and maintained in a tissue bath.  (vitrum =glass, Latin)

In vivo = a procedure carried out with tissue in normal position within the body.  (vivo = I live, Latin) 

Inter = between (Latin) (N.B. do not confuse with intra!)
Intercellular = between cells
Intercostals = muscles that occupy the spaces between the ribs

Intra = inside (Latin)
Intracellular = inside cells
Intraperitoneal = an injection given into the abdominal cavity

Ipsi = same, self (Latin)
Ipsilateral = on the same side

Iso- = prefix denoting equality, uniformity and similarity
Isotonic = having the same osmolarity or (in physiology) effective osmolarity (taking account of the solute permeability of cell membranes).
Isodactylism = a congenital defect in which all the fingers are the same length.

-itis = suffix denoting inflammation of an organ, tissue etc.
Arthritis = inflammation of a joint
Peritonitis = inflammation of the peritoneum 

Kal- = relating to potassium (Kalium – hence symbol K, Latin)
Hypokalaemia = low blood potassium
Hyperkalaemia = high blood potassium

Late = wide, far (Latin)
Lateral = in anatomy relates to the region or parts of the body that are furthest from the median plane

-logy = suffix denoting field of study
Cytology = study of cells
Nephrology = study, investigation and management of the diseases of the kidney

-lysis = disruption, destruction or release
Haemolysis = destruction of red cells
Anxiolytic = causing relief from anxiety

Medial = relating to or situated in the central region of an organ, tissue or the body    (from medius = mid, middle, Latin)
Median plane (sagittal plane) = plane dividing the body or an organ into equal right and left halves
Mediastinum = space in the thorax between the two pleural sacs that contains amongst other things the heart

Mening- = relating to the meninges (membranes covering the brain) (Greek)
Meningitis = inflammation of the meninges

Muco- = prefix denoting mucus (Latin)
Mucociliary = the process by which cilia move a thin film of mucus from the lower and upper respiratory tracts towards the digestive tract
Mucosa = mucous membrane, a moist membrane that lines many tubular structures and cavities e.g. nasal cavity

My- = prefix denoting muscle
Myoblast = a cell that develops into a muscle fibre
Myocardial infarction = death of a segment of heart muscle, which follows interruption of its blood supply

Natri = relating to sodium (Natrium - hence symbol Na, Latin)
Natriuretic factor = factor leading to extra sodium appearing in the urine
Natriuresis = excretion of sodium in the urine

Nephro- = prefix denoting the kidneys (Greek)
(N.B see renal = relating to the kidney, Latin)
Nephritis = inflammation of the kidney
Nephron = the active unit of excretion in the kidney

Neuro- = prefix denoting nerves or the nervous system
Neurolemma = sheath of the axon of the nerve fibre
Neurone = basic functional unit of the nervous system; a cell specialized to transmit electrical nerve impulses

Normo = normal (Latin)
Normocapnic = normal carbon dioxide levels within the blood.
Normotensive = describes the state in which the arterial blood pressure is within the normal range

-oma = suffix denoting a tumour
Hepatoma = tumour of the liver
Lymphoma = tumour of the lymph nodes

Oral = relating to the mouth (os, oris = mouth, Latin)
Oral cavity = the mouth
Oral contraceptive = ‘the pill’ (taken via the mouth)
(N.B. do not confuse with aural = relating to the ear)
Ortho- = prefix denoting straight
Orthodontics = branch of dentistry concerned with the treatment of the irregularities of the teeth.
Orthopaedics = practice of the correction of deformities caused by disease or damage to the bone and joints of the skeleton

-osis = a diseased condition that involves the preceding part of the word
e.g. Tuberculosis, Nephrosis 

Oste(o)- = relating to bone [Grk]

Para = alongside (Latin)
Parathyroid = gland beside the thyroid
Paranasal = near the nasal cavity

Peri = surrounding or around (Latin)
Perineurium = sheath around nerve.
Perinatal = around the time of birth.

-physis = growth
Hypophysis = outgrowth under the brain i.e. the pituitary gland

-plegic = suffix denoting paralysis
Diplegia = paralysis of both sides of the body, particularly the legs
Hemiplegia = paralysis of one side of the body

Pneo- = prefix denoting breathing
Pneumo- = prefix denoting the presence of air or gas
Pneumothorax = air in the pleural cavity
Pneumocephalus = the presence of air within the skull

Pneumon- = prefix denoting the lungs
Pneumonia = inflammation of the lung caused by bacteria, in which the alveoli become filled with inflammatory cells and the lung becomes solid
Pneumonectomy = surgical removal of the lung

Poly- = prefix denoting many, multiple
Polysome = a group of ribosomes linked together by messenger RNA molecules, formed during translation process of protein synthesis
Polysaccharide = carbohydrate formed from many monosaccharide molecules joined in long linear and branched chains

Post = after, behind (Latin)
Posterior = near or nearer backend or tail
Posteroanterior = from the back to the front

Proximal = situated close to the origin or point of attachment or close to the median line of the body (from proximus = nearest, Latin)
Quadri- = prefix denoting four (Latin)
Quadriceps = a great extensor muscle of the leg, situated in the thigh and divided into four distinct portions
Quadriplegia = paralysis affecting all four limbs
Renal = relates to the kidney (Latin)
(N.B. see nephro- = prefix denoting the kidney, Greek)
Renal artery = either of the two arteries arising from the abdominal aorta and supplying the kidneys.
Renal tubule = fine tubular part of nephron through which water and certain dissolved substances are reabsorbed back into the blood

-rrhage = denotes excessive or abnormal flow or discharge from an organ or part
haemorrhage = excessive bleeding
menorrhagia = excessive menstrual flow

-rrhoea = flow or discharge from an organ or part 
Diarrhoea = frequent bowel evacuations or passage of abnormally soft faeces.
Rhinorrhoea = flow from the nose

Saccharo- = prefix denoting sugar
Disaccharide = carbohydrate consisting of two linked monosaccharide units
Polysaccharide = carbohydrate formed from many monosaccharide molecules joined in long linear and branched chains

Sagittal = an anatomical plane that divides the body longitudinally into left and right parts, parallel to the median plane.

Stasis = constancy, cessation of movement (Latin)
Homeostasis = physiological process by which the internal systems of the body are maintained at equilibrium, despite variations in the external conditions.

-stoma = mouth
Stoma = in surgery, an artificial opening of a tube
tracheostomy = an artificial opening (mouth) in the trachea
colostomy = an artificial opening in the colon that has been brought to the surface of the abdomen
ileostomy = an artificial opening in the colon that has been brought to the surface of the abdomen

Sub = under, beneath (Latin)
Sub-lingual = under the tongue
Subcutaneous = beneath the skin

Super = above (Latin)
Superior = situated uppermost in the body related to another structure or surface
Superficial = situated at or close to a surface

Supine = lying on the back (often a term used to describe lazy people) (Latin)

Supra = above (Latin)
Suprapubic region = area found above the pubic region (N.B. also known as the hypogastric region.)
Suprarenal = above the kidney

Tachy- = prefix denoting fast, rapid
Tachypnoea = rapid breathing
Tachycardia = rapid heart beat

-thermic = relating to temperature (Latin)
Exothermic = a reaction in which heat is given out
Thermoreceptor = a sensory nerve ending that responds to hot and cold

-tomy = cutting
Lobotomy = incising a lobe of a organ
Gastrotomy = a surgical incision into the stomach

Topo- = prefix denoting place, position and location
Topical = local, used for the route of administration of a drug that is applied directly to the part being treated
Topography = study of the different regions of the body including how the parts relate to surrounding structures
(N.B. do not confuse with either, tropic = related to direction, or trophic = related to nutrition e.g. trophotropic = turning towards food

Toxi- = prefix denoting poisonous, toxic
Toxin = poison produced by a living organism, usually a bacterium
Toxaemia = blood poisoning that is caused by toxins formed by bacteria growing in a local site of infection

Trans = across (Latin)
Transverse = In anatomy, situated at right angles to the long axis of the body
Transverse plane (horizontal plane) = plane dividing organ into top and bottom halves

Tri- = prefix denoting three (Latin)
Tricuspid valve = valve in heart between right atrium and right ventricle, made up of three cusps
Triceps = a muscle with three heads of origin

-trophic, -trophy = relating to nutrition (Greek)
Dystrophy = disordered nutrition
Atrophy = wasting, reduction in size
Hypertrophy = over-development

-tropic, -tropy, etc. = attracted to, turning towards, or affecting. (Greek)
Neurotropic virus = one targetting nerves
Phototropism = orienting to light

Uni- = prefix denoting one
Unilateral = in anatomy, relating to or affecting one side of the body or one side of an organ or other part

-uresis = relating to or appearing in the urine
proteinuresis = protein in the urine
diuresis = extra urine

Vaso- = relating to a vessel, usually a blood vessel (Latin)
Vasectomy = removal of part of vas deferens
Vasoactive = affecting the diameter of blood vessels

Ventral = front (venter =  stomach, abdomen Latin)
ventro-medial = direction towards the front and the midline
ventricle = fluid filled chamber in the heart/brain ('small belly')