Medical Terminology and Word Building
The Medical Terminology and Word Building domain tests whether you can decompose unfamiliar clinical terms into their parts, build terms from a definition, and apply plural and abbreviation conventions accurately. Expect items that combine a prefix, root, combining vowel, and suffix in one word, plus questions on eponyms and error-prone abbreviations.
Core rules
- A root carries the core meaning (cardi- = heart; nephr- = kidney). A combining form is root + vowel, usually o, used to link parts (cardi/o). The vowel is retained before a suffix beginning with a consonant and dropped before one beginning with a vowel: cardiology but carditis. When two roots are joined, a combining vowel usually links them.
- Prefixes change location, number, time, or quality: peri- around, intra- within, inter- between, sub- below, supra- above, brady- slow, tachy- fast, dys- difficult or abnormal, hyper- excess, hypo- deficient.
- Suffixes signal condition, procedure, or specialty: -itis inflammation, -ectomy excision, -otomy incision, -ostomy creation of an opening, -plasty repair, -scopy viewing, -gram record, -graphy recording process, -emia blood condition, -uria urine condition, -pnea breathing.
- Plurals: -a to -ae (vertebrae), -us to -i (bronchi), -um to -a (atria), -is to -es (diagnoses), -x to -ces (thoraces). Do not pluralize eponyms with an apostrophe: Foley catheters, Cushing reflexes.
Worked example
Build and parse cholecystectomy. Chole- means bile, cyst- means bladder (gallbladder), and -ectomy means surgical removal. The combining vowel o links chol/e to cyst, and the final root drops its vowel before the vowel-initial suffix: chole + cyst + ectomy. The term therefore means removal of the gallbladder. If the dictation says cholecystostomy, the suffix changes to -ostomy, meaning a new opening is created, not that the organ is removed.
Traps
Do not confuse -ectomy, -otomy, and -ostomy; exam items often hinge on that single suffix. Keep ileum (small intestine) separate from ilium (pelvic bone), and dysphagia (difficulty swallowing) separate from dysphasia (language difficulty). Watch for a dropped combining vowel that changes pronunciation or meaning, and resist adding apostrophes to eponyms.