Medical Terminology Dictionary
Almost every medical word is built from a handful of Greek and Latin parts. Learn thirty of them and you can take apart words you have never met: peri-card-itis is inflammation around the heart, and you did not need to look it up.
Reviewed by Dr. Mohan Gayenlast reviewed
50 entries
Suffixes — what is happening
- -itisInflammation of. Appendicitis, arthritis, hepatitis, dermatitis.
- -osisA condition or process, usually abnormal and usually not inflammatory. Fibrosis, thrombosis, cirrhosis.
- -ectomySurgical removal of. Appendectomy, hysterectomy, nephrectomy.
- -otomyCutting into. Tracheotomy, laparotomy.
- -ostomyMaking a permanent opening. Colostomy, tracheostomy.
- -oscopyLooking inside with an instrument. Endoscopy, colonoscopy, bronchoscopy.
- -plastySurgical repair or reshaping. Angioplasty, rhinoplasty.
- -algia / -dyniaPain. Neuralgia, myalgia.
- -emia / -aemiaA blood condition. Anaemia, hyperkalaemia, septicaemia.
- -uriaA urine condition. Haematuria (blood), proteinuria (protein), polyuria (a lot).
- -pathyDisease of. Neuropathy, cardiomyopathy, retinopathy.
- -megalyEnlargement. Hepatomegaly, cardiomegaly, splenomegaly.
- -peniaA deficiency or shortage. Thrombocytopenia, neutropenia, osteopenia.
- -omaA tumour or swelling — not necessarily cancerous. Lipoma, haematoma, carcinoma.
Roots — where
- Cardi(o)-Heart. Cardiology, myocardium, tachycardia.
- Hepat(o)-Liver. Hepatitis, hepatomegaly.
- Nephr(o)- / Ren(o)-Kidney. Nephritis, nephrology, renal.
- Gastr(o)-Stomach. Gastritis, gastroenterology.
- Enter(o)-Intestine. Enteritis, gastroenteritis.
- Pulmon(o)- / Pneum(o)-Lung or air. Pulmonary, pneumonia, pneumothorax.
- Neur(o)-Nerve. Neurology, neuropathy, neuralgia.
- Oste(o)-Bone. Osteoporosis, osteomyelitis.
- My(o)-Muscle. Myocardium, myalgia, myopathy.
- Derm(at)(o)-Skin. Dermatitis, dermatology.
- Haem(o)- / Hem(o)-Blood. Haemorrhage, haematology, haemoglobin.
- Angi(o)- / Vas(o)-Vessel. Angiography, vasodilation.
- Encephal(o)-Brain. Encephalitis, encephalopathy.
Prefixes — how much
- Hyper-Above normal, excessive. Hypertension, hyperglycaemia, hyperthyroidism.
- Hypo-Below normal, deficient. Hypotension, hypoglycaemia, hypothyroidism.
- Brady-Slow. Bradycardia is a slow heart rate.
- Tachy-Fast. Tachycardia is a fast heart rate; tachypnoea is fast breathing.
- Poly-Many or much. Polyuria, polydipsia (a lot of thirst), polyarthritis.
- Oligo-Few or little. Oliguria is passing very little urine.
Prefixes — how
- Dys-Difficult, painful or abnormal. Dyspnoea, dysphagia (difficulty swallowing), dysuria.
- A- / An-Without. Anaemia, apnoea, anuria, asymptomatic.
Prefixes — where
- Peri-Around. Pericardium is the sac around the heart.
- Endo-Inside. Endocarditis, endoscopy, endometrium.
- Epi-Upon or over. Epidermis, epigastric.
- Sub-Under. Subcutaneous, sublingual.
- Inter-Between. Intercostal is between the ribs.
- Intra-Within. Intravenous, intramuscular, intracranial.
Words worth knowing
- IdiopathicOf unknown cause. It is an honest label, not a diagnosis of exclusion dressed up.
- IatrogenicCaused by medical treatment itself.
- Acute vs chronicAcute means sudden and short-lived; chronic means long-lasting. Neither describes severity — a chronic condition can be mild, an acute one fatal.
- Benign vs malignantBenign does not invade or spread; malignant does. Benign does not mean harmless — a benign brain tumour can still be dangerous by position.
- PrognosisThe expected course and outcome of a condition.
- AetiologyThe cause of a disease.
- ProphylaxisTreatment given to PREVENT something rather than to treat it.
- ContraindicationA reason a treatment must not be given to a particular person.
- Sign vs symptomA symptom is what you report; a sign is what the doctor finds. Pain is a symptom, a rash is a sign.
Numbers are listed for 55 countries and can change — if your country is not here, or you are not sure, 112 reaches emergency services across the European Union and works from a mobile in much of the world. Do not drive yourself.
This is general health information for education, not medical advice, and not a diagnosis. It cannot see you, your history, your allergies or your medicines. Never use it to start, stop or change a treatment, and never let it delay you seeking care. If you are worried about symptoms, speak to a qualified doctor; if they are severe or sudden, seek emergency help.
Where this comes from: Standard medical word roots, prefixes and suffixes.
Where this is written from: This site is written from Indian clinical practice. Drug availability and brand names, vaccination schedules, national health programmes and some reference cut-offs differ between countries — a schedule or a threshold that is standard here may not be standard where you are. If you are reading outside India, check anything on this page against your own country’s guidance before you act on it.
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The word parts that let you decode a term you have never seen.