Notes on derivation of medical terms
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Derivation of Medical Terms
Medical terminology is largely derived from Greek and Latin. Most terms can be understood by dividing them into word parts and then combining their meanings.
1. Basic components
| Component | Function | Example |
|---|---|---|
| Prefix | Comes before the root and modifies meaning | **brady-**cardia = slow heart rate |
| Word root | Gives the central meaning, often a body part | cardi = heart |
| Combining vowel | Usually o; makes pronunciation easier | cardi/o/logy |
| Suffix | Comes at the end; commonly indicates a condition, procedure, or specialty | cardi/o/logy = study of the heart |
| Combining form | Word root + combining vowel | gastr/o = stomach |
A useful formula is:
Prefix + root/combining form + suffix
For example:
peri/card/itis
- peri- = around
- cardi = heart
- -itis = inflammation
Meaning: inflammation around the heart.
Medical terms can be systematically decoded from prefixes, roots, suffixes, and combining vowels, as outlined in the NCBI medical terminology text.
2. Rules for combining vowels
The most common combining vowel is o.
-
Use a combining vowel between a root and a suffix that starts with a consonant.
- arthr/o/pathy
- arthr = joint; -pathy = disease
- Arthropathy: disease of a joint.
-
Usually do not use a combining vowel when the suffix begins with a vowel.
- hepat/ic, not hepatoic
- Hepatic: relating to the liver.
-
Use a combining vowel between two word roots, even if the second root begins with a vowel.
- oste/o/arthr/itis
- Osteoarthritis: disease involving bone and joint inflammation/degeneration.
-
Do not insert a combining vowel between a prefix and a root.
- sub/hepat/ic
- Subhepatic: below the liver.
3. Common prefixes
| Prefix | Meaning | Example | Meaning of example |
|---|---|---|---|
| a-, an- | without, absence of | anemia | lack of normal red blood cells/hemoglobin |
| anti- | against | antibiotic | agent against bacteria |
| brady- | slow | bradycardia | slow heart rate |
| tachy- | fast | tachypnea | rapid breathing |
| dys- | difficult, painful, abnormal | dysuria | painful or difficult urination |
| hyper- | excessive, above normal | hypertension | high blood pressure |
| hypo- | deficient, below normal | hypoglycemia | low blood glucose |
| intra- | within | intravenous | within a vein |
| inter- | between | intercostal | between the ribs |
| peri- | around | pericardium | membrane around the heart |
| endo- | within, inner | endocardium | inner lining of the heart |
| ecto-, exo- | outside, outer | ectopic | occurring outside the normal site |
| pre- | before | prenatal | before birth |
| post- | after | postoperative | after surgery |
| poly- | many | polyuria | excessive urine output |
| oligo- | few, scanty | oliguria | reduced urine output |
4. Common roots and combining forms
| Root / combining form | Meaning | Example |
|---|---|---|
| cardi/o | heart | cardiology |
| neur/o | nerve | neurology |
| gastr/o | stomach | gastritis |
| enter/o | intestine | enteropathy |
| hepat/o | liver | hepatomegaly |
| nephr/o | kidney | nephrology |
| cyst/o | urinary bladder or sac | cystoscopy |
| oste/o | bone | osteoporosis |
| arthr/o | joint | arthritis |
| my/o | muscle | myopathy |
| derm/o, dermat/o | skin | dermatitis |
| hemat/o, hem/o | blood | hematology |
| pneum/o, pulmon/o | lung | pneumonia, pulmonology |
| encephal/o | brain | encephalitis |
| ophthalm/o | eye | ophthalmology |
| ot/o | ear | otitis |
| rhin/o | nose | rhinitis |
| laryng/o | larynx | laryngitis |
| phleb/o | vein | phlebitis |
5. Common suffixes
A. Conditions and diseases
| Suffix | Meaning | Example |
|---|---|---|
| -itis | inflammation | tonsillitis |
| -osis | abnormal condition, often increase or degeneration | leukocytosis |
| -pathy | disease | neuropathy |
| -emia | blood condition | bacteremia |
| -uria | urine condition | hematuria |
| -algia, -dynia | pain | neuralgia, gastrodynia |
| -megaly | enlargement | splenomegaly |
| -malacia | softening | osteomalacia |
| -penia | deficiency | leukopenia |
| -sclerosis | hardening | arteriosclerosis |
| -stenosis | narrowing | aortic stenosis |
| -rrhage, -rrhagia | excessive bleeding | hemorrhage |
| -rrhea | flow, discharge | diarrhea |
| -lysis | breakdown, destruction | hemolysis |
B. Diagnostic procedures and examination
| Suffix | Meaning | Example |
|---|---|---|
| -scopy | visual examination | endoscopy |
| -graphy | process of recording/imaging | angiography |
| -gram | record or image | electrocardiogram |
| -meter | measuring instrument | spirometer |
| -metry | process of measuring | spirometry |
C. Surgical procedures
| Suffix | Meaning | Example |
|---|---|---|
| -ectomy | surgical removal | appendectomy |
| -otomy | incision or cutting into | tracheotomy |
| -ostomy | surgically created opening | colostomy |
| -plasty | surgical repair or reconstruction | rhinoplasty |
| -pexy | surgical fixation | nephropexy |
| -centesis | surgical puncture to remove fluid | thoracentesis |
D. Specialties and specialists
| Suffix | Meaning | Example |
|---|---|---|
| -logy | study of | pathology |
| -logist | specialist in the study of | cardiologist |
| -iatry | medical treatment or specialty | psychiatry |
| -ician | specialist | pediatrician |
6. Method for deriving a medical term
Use this sequence:
- Start with the suffix: it often tells you the condition or procedure.
- Identify the root(s): usually identifies the organ or tissue.
- Identify the prefix: gives location, time, number, speed, or severity.
- Combine the meanings in plain English.
Examples
Hypoglycemia
- hypo- = low
- glyc = sugar
- -emia = blood condition
Meaning: low sugar in the blood.
Tachycardia
- tachy- = rapid
- cardi = heart
- -ia = condition
Meaning: condition of a rapid heart rate.
Nephrectomy
- nephr = kidney
- -ectomy = surgical removal
Meaning: surgical removal of a kidney.
Osteoarthritis
- oste/o = bone
- arthr = joint
- -itis = inflammation
Literal meaning: inflammation involving bone and joint.
In present clinical usage, it refers mainly to a degenerative joint disease.
Endoscopy
- endo- = within
- -scopy = visual examination
Meaning: visual examination inside the body.
7. Singular and plural forms
Many medical nouns retain Greek or Latin plural forms.
| Singular | Plural |
|---|---|
| bacterium | bacteria |
| bronchus | bronchi |
| diagnosis | diagnoses |
| appendix | appendices |
| cortex | cortices |
| vertebra | vertebrae |
| atrium | atria |
| thrombus | thrombi |
| carcinoma | carcinomata/carcinomas |
8. Important caution
The literal derivation helps in understanding terms, but some established medical words do not perfectly match modern clinical meaning. For example, arthritis literally means joint inflammation, yet clinical conditions ending in
-itis may not always have active inflammation as their main process.For practice, break every new term into: prefix + root + suffix, then translate each part before stating the complete meaning.
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