Medical Prefixes, Suffixes, and Root Words
Most medical terms are built from parts: a prefix that modifies, a root that names the body part, and a suffix that names the condition or procedure. Pericarditis is peri- (around) + card (heart) + -itis (inflammation). Knowing the common parts lets you read, and spell, a term you have never seen.
Last reviewed October 8, 2026.
On this page: how terms are built · prefixes · suffixes · root words · easily confused
How terms are built
| Term | Parts | Meaning |
|---|---|---|
| gastroenteritis | gastr/o (stomach) + enter (intestine) + -itis | inflammation of the stomach and intestines |
| hepatosplenomegaly | hepat/o (liver) + splen/o (spleen) + -megaly | enlarged liver and spleen |
| bradycardia | brady- (slow) + card (heart) + -ia (condition) | a slow heart rate |
| nephrolithiasis | nephr/o (kidney) + lith (stone) + -iasis (condition) | kidney stones |
| cholecystectomy | chole (bile) + cyst (bladder) + -ectomy | removal of the gallbladder |
| thrombocytopenia | thromb/o (clot) + cyt/o (cell) + -penia | too few platelets |
Prefixes
| Prefix | Meaning | Example |
|---|---|---|
| a-, an- | without, absence of | apnea, anemia |
| anti- | against | antibiotic, anticoagulant |
| brady-, tachy- | slow, fast | bradycardia, tachypnea |
| dys- | difficult, abnormal | dysphagia, dyspnea |
| endo-, epi- | within; upon | endoscopy, epidural |
| hemi- | half | hemiparesis |
| hyper-, hypo- | above or too much; below or too little | hypertension, hypoglycemia |
| inter-, intra- | between; within | intercostal, intravenous |
| macro-, micro- | large, small | macrocytic, microcytic |
| neo- | new | neonatal, neoplasm |
| peri-, para- | around; beside | pericardium, paravertebral |
| poly-, oligo- | many or much; few or little | polyuria, oliguria |
| pre-, post- | before, after | preoperative, postpartum |
| sub-, supra- | below; above | subcutaneous, suprapubic |
| trans- | across, through | transdermal, transthoracic |
| uni-, bi-, tri-, quadri- | one, two, three, four | bilateral, quadriplegia |
Suffixes
| Suffix | Meaning | Example |
|---|---|---|
| -algia, -dynia | pain | myalgia, arthralgia |
| -centesis | puncture to remove fluid | thoracentesis, paracentesis |
| -ectomy | surgical removal | appendectomy |
| -otomy | incision into | laparotomy, thoracotomy |
| -ostomy | surgical opening | colostomy, tracheostomy |
| -plasty | surgical repair or reshaping | angioplasty |
| -scopy | looking inside with a scope | colonoscopy, bronchoscopy |
| -gram, -graphy | a record; the process of recording | electrocardiogram, angiography |
| -itis | inflammation | appendicitis, cellulitis |
| -osis, -iasis | condition, often abnormal | fibrosis, cholelithiasis |
| -emia | condition of the blood | hyperkalemia, bacteremia |
| -uria | condition of the urine | hematuria, dysuria |
| -penia, -cytosis | too few; too many cells | neutropenia, leukocytosis |
| -megaly | enlargement | splenomegaly, cardiomegaly |
| -oma | tumor, mass | lipoma, carcinoma |
| -pathy | disease | neuropathy, cardiomyopathy |
| -plegia, -paresis | paralysis; weakness | hemiplegia, hemiparesis |
| -pnea | breathing | dyspnea, orthopnea |
| -rrhage, -rrhea | bursting forth; flow | hemorrhage, diarrhea |
| -lysis, -stasis | breakdown; stopping | hemolysis, hemostasis |
Root words
| Root | Meaning | Example |
|---|---|---|
| angi/o, vas/o | vessel | angiogram, vasodilation |
| arthr/o | joint | arthritis, arthroscopy |
| cardi/o | heart | cardiology, tachycardia |
| cephal/o, encephal/o | head; brain | cephalic, encephalopathy |
| chol/e, cyst/o | bile; bladder or sac | cholestasis, cystoscopy |
| derm/o, dermat/o, cutane/o | skin | dermatitis, subcutaneous |
| gastr/o, enter/o, col/o | stomach; small intestine; colon | gastritis, enteritis, colitis |
| hem/o, hemat/o | blood | hemoptysis, hematuria |
| hepat/o | liver | hepatitis, hepatomegaly |
| my/o | muscle | myalgia, myocardium |
| nephr/o, ren/o | kidney | nephrology, renal |
| neur/o | nerve | neuropathy, neurology |
| oste/o | bone | osteoporosis, osteomyelitis |
| pneum/o, pulmon/o | lung or air; lung | pneumothorax, pulmonary |
| thromb/o | clot | thrombosis, thrombectomy |
Easily confused
A few pairs cause most spelling and reading errors in notes: ileum (the last part of the small intestine) and ilium (the pelvic bone); hyper- and hypo-; inter- and intra-; -ectomy, -otomy, and -ostomy; peri- and para-; and prostate, the gland, against prostrate, lying face down.
Practice typing it
Long built-up terms are where spelling slips: doubled letters, silent vowels, and the combining o. The trainer's disease, anatomy, and procedure categories are full of them.
Disease, anatomy, and procedure terms Terms spelled out in full
Preset links open the trainer with those settings already applied; you can change them afterward.
For the letter patterns that cause most terminology typos, see medical terminology typing practice.
Common questions
What is the difference between -ectomy, -otomy, and -ostomy?
-ectomy means cutting something out, as in appendectomy, removal of the appendix. -otomy means cutting into it, as in laparotomy, an incision into the abdomen. -ostomy means making a new opening, as in colostomy, an opening from the colon through the abdominal wall.
What is a combining vowel?
The vowel, usually o, that joins a root to the next part, as in cardi-o-logy. It is dropped when the next part already starts with a vowel: gastr plus -itis is gastritis, not gastroitis.
Which prefixes are most often confused?
hyper- (above, too much) and hypo- (below, too little); inter- (between) and intra- (within); ante- (before) and anti- (against); dys- (difficult, abnormal) and dis- (apart, reversal).
What does -emia mean?
A condition of the blood: anemia is too little hemoglobin or too few red cells, hyperkalemia is high blood potassium, and bacteremia is bacteria in the blood.
Sources
- MedlinePlus (US National Library of Medicine). Understanding Medical Words.