29.1 Medical Word Building: Root Words, Combining Forms, Prefixes & Suffixes
Key Takeaways
- A medical term is built from a word root that carries the core meaning, an optional combining vowel (usually o) that joins parts, a prefix that modifies the beginning, and a suffix that modifies the end.
- The combining vowel is retained when the suffix begins with a consonant and dropped when the suffix begins with a vowel, so it is osteomyelitis but osteitis and gastrectomy but gastroenterology.
- The imaging suffixes are examined as a set: -graphy is the process of recording, -gram is the record produced, -graph is the recording instrument, -scopy is direct visual examination, and -scope is the instrument used.
- Procedure suffixes must be distinguished precisely: -ectomy is surgical removal, -otomy is a surgical incision, -ostomy is the creation of an artificial opening, -plasty is surgical repair, -pexy is surgical fixation, and -desis is surgical fusion.
- Terms are analysed from the suffix backwards: read the suffix first, then the prefix, then the root, so that gastroenterostomy resolves as the creation of an opening between the stomach and the small intestine.
Last updated: August 2026
29.1 Medical Word Building: Root Words, Combining Forms, Prefixes & Suffixes
Medical Terminology is a full topic in the Patient Care and Management subject, worth 15 items — the same weight as Human Anatomy and Physiology, as Administration and Leadership, as Professional Ethics and Jurisprudence, and as Radiologic Pathology. Its first sub-topic, Medical Root Words and Vocabulary Related to Radiologic Technology, carries 8 items and asks the examinee to apply the word-building process, its Latin root word, prefixes and suffixes. This is arithmetic, not memorisation: learn the system and any term decodes.
1. The Four Building Blocks
| Element | Function | Example |
|---|---|---|
| Word root | Carries the fundamental meaning, usually a body part | cardi = heart |
| Combining vowel | Joins a root to another root or to a suffix; almost always o | cardi o |
| Combining form | Root plus combining vowel, written root/o | cardi/o |
| Prefix | Placed before the root to modify it | peri- = around |
| Suffix | Placed after the root to modify it | -itis = inflammation |
Assembled: peri + cardi + itis = pericarditis, inflammation of the tissue around the heart.
The combining-vowel rule — examined constantly
- Keep the combining vowel when the suffix begins with a consonant. oste/o + -myelitis = osteomyelitis; gastr/o + -scopy = gastroscopy.
- Drop the combining vowel when the suffix begins with a vowel. oste/o + -itis = osteitis; gastr/o + -ectomy = gastrectomy.
- Always keep the combining vowel between two roots, even when the second root begins with a vowel. gastr/o + enter/o + -logy = gastroenterology.
- A prefix ending in a vowel before a root beginning with a vowel usually loses the vowel: endo- + arteritis becomes endarteritis.
How to read a term
Read the suffix first, then the prefix, then the root(s).
- Gastroenterostomy → -stomy (creation of an opening) + gastr/o (stomach) + enter/o (small intestine) = surgical creation of an opening between the stomach and the small intestine.
- Cholecystectomy → -ectomy (removal) + cholecyst (gallbladder) = surgical removal of the gallbladder.
- Hysterosalpingography → -graphy (process of recording) + hyster/o (uterus) + salping/o (fallopian tube) = radiographic recording of the uterus and fallopian tubes. That single term describes the entire examination taught in Section 15.3.
2. Anatomical Roots and Combining Forms
| Combining form | Meaning | Combining form | Meaning | |
|---|---|---|---|---|
| oste/o | bone | cardi/o | heart | |
| my/o | muscle | angi/o, vas/o | vessel | |
| arthr/o | joint | phleb/o, ven/o | vein | |
| chondr/o | cartilage | arteri/o | artery | |
| crani/o | skull | hemat/o, haem/o | blood | |
| spondyl/o, vertebr/o | vertebra | pulmon/o, pneum/o | lung, air | |
| cost/o | rib | bronch/o | bronchus | |
| stern/o | sternum | thorac/o | chest | |
| derm/o, cutane/o | skin | gastr/o | stomach | |
| cephal/o | head | enter/o | small intestine | |
| encephal/o | brain | col/o | colon | |
| myel/o | spinal cord or bone marrow | hepat/o | liver | |
| neur/o | nerve | cholecyst/o | gallbladder | |
| rhin/o, nas/o | nose | chol/e | bile | |
| ot/o, aur/i | ear | pancreat/o | pancreas | |
| ophthalm/o, ocul/o | eye | nephr/o, ren/o | kidney | |
| odont/o, dent/i | tooth | cyst/o, vesic/o | urinary bladder | |
| gnath/o | jaw | ureter/o | ureter | |
| mamm/o, mast/o | breast | urethr/o | urethra | |
| hyster/o, metr/o, uter/o | uterus | pyel/o | renal pelvis | |
| salping/o | fallopian tube (or eustachian tube) | splen/o | spleen | |
| oophor/o, ovari/o | ovary | aden/o | gland | |
| orchi/o, test/o | testis | lymph/o | lymph | |
| radi/o | radiation, x-ray, or the radius | tom/o | to cut, section | |
| fluor/o | luminous, flowing | son/o, ech/o | sound | |
| therm/o | heat | electr/o | electricity |
Two deliberate traps. Radi/o means both x-ray/radiation and the radius bone; context decides. Salping/o means both fallopian tube and eustachian tube; salpingography of the ear is a real, if rare, procedure.
3. Prefixes
Position and direction
| Prefix | Meaning | Prefix | Meaning |
|---|---|---|---|
| ante-, pre-, pro- | before, in front of | post-, retro- | after, behind |
| sub-, infra-, hypo- | below, under | supra-, epi-, hyper- | above, upon |
| inter- | between | intra- | within |
| extra-, exo-, ecto- | outside | endo-, end- | within, inner |
| peri- | around | circum- | around |
| trans- | across, through | dia- | through, complete |
| ab- | away from | ad- | toward |
| contra- | against, opposite | ipsi- | same |
| meso-, medi- | middle | para- | beside, near, abnormal |
Note the near-collision: intercostal (between the ribs) versus intravenous (within a vein). One letter changes the meaning entirely.
Number and quantity
| Prefix | Meaning | Prefix | Meaning |
|---|---|---|---|
| mono-, uni- | one | bi-, di- | two |
| tri- | three | quadri-, tetra- | four |
| poly-, multi- | many | hemi-, semi- | half |
| oligo- | few, scanty | pan- | all |
| micro- | small | macro-, mega- | large |
Negation, degree and colour
| Prefix | Meaning | Prefix | Meaning |
|---|---|---|---|
| a-, an- | without, absence of | anti- | against |
| dys- | painful, difficult, abnormal | eu- | normal, good |
| brady- | slow | tachy- | fast |
| hyper- | excessive, above normal | hypo- | deficient, below normal |
| neo- | new | necr/o- | death |
| auto- | self | hetero- | different |
| leuk/o- | white | melan/o- | black |
| erythr/o- | red | cyan/o- | blue |
| xanth/o- | yellow | chlor/o- | green |
4. Suffixes
Diagnostic and symptomatic
| Suffix | Meaning | Example |
|---|---|---|
| -itis | inflammation | osteomyelitis |
| -osis | abnormal condition | osteoporosis |
| -oma | tumour, mass | osteosarcoma |
| -pathy | disease | neuropathy |
| -algia, -dynia | pain | neuralgia |
| -megaly | enlargement | cardiomegaly |
| -sclerosis | hardening | atherosclerosis |
| -stenosis | narrowing | spinal stenosis |
| -ectasis, -ectasia | dilation, expansion | bronchiectasis, sialectasis |
| -malacia | softening | osteomalacia |
| -lysis | breakdown, destruction, separation | osteolysis |
| -ptosis | drooping, prolapse | nephroptosis |
| -rrhage, -rrhagia | bursting forth, excessive flow | haemorrhage |
| -rrhea | flow, discharge | rhinorrhoea |
| -rrhexis | rupture | angiorrhexis |
| -emia | blood condition | anaemia, hypoxaemia |
| -uria | urine condition | haematuria, dysuria |
| -penia | deficiency | leukopenia |
| -cele | hernia, swelling | meningocele |
| -plegia | paralysis | hemiplegia |
| -genic, -genesis | producing, origin | osteogenic, carcinogenesis |
Surgical and procedural
| Suffix | Meaning | Example |
|---|---|---|
| -ectomy | surgical removal | appendectomy |
| -otomy, -tomy | surgical incision | craniotomy |
| -ostomy, -stomy | creation of an artificial opening | colostomy |
| -plasty | surgical repair or reshaping | angioplasty |
| -pexy | surgical fixation | nephropexy |
| -desis | surgical fusion | arthrodesis |
| -rrhaphy | suture | herniorrhaphy |
| -centesis | surgical puncture to withdraw fluid | thoracentesis |
| -tripsy | crushing | lithotripsy |
The -ectomy / -otomy / -ostomy triad is the single most examined suffix set in medical terminology. Removal, incision, opening.
Imaging and instrument suffixes
| Suffix | Meaning | Example |
|---|---|---|
| -graphy | the process of recording | radiography, sialography |
| -gram | the record produced | radiogram, arthrogram, hysterosalpingogram |
| -graph | the instrument that records | radiograph (as the device), electrocardiograph |
| -scopy | direct visual examination | fluoroscopy, endoscopy, sialendoscopy |
| -scope | the instrument used to look | fluoroscope, endoscope |
| -meter | instrument that measures | dosimeter, densitometer, pelvimeter |
| -metry | the process of measuring | pelvimetry, densitometry, sonometry |
| -logy | the study of | radiology |
| -logist | one who studies or specialises | radiologist |
5. Decoding Practice
| Term | Breakdown | Meaning |
|---|---|---|
| Cholangiopancreatography | chol/e bile + angi/o vessel + pancreat/o pancreas + -graphy | Recording of the biliary ducts and pancreatic duct |
| Myelography | myel/o spinal cord + -graphy | Radiographic recording of the spinal cord and subarachnoid space |
| Arthrogram | arthr/o joint + -gram | The image produced of a joint |
| Nephrolithotomy | nephr/o kidney + lith/o stone + -otomy | Surgical incision into the kidney to remove a stone |
| Pyelonephritis | pyel/o renal pelvis + nephr/o kidney + -itis | Inflammation of the renal pelvis and kidney |
| Bronchiectasis | bronchi bronchus + -ectasis | Abnormal dilation of the bronchi |
| Spondylolisthesis | spondyl/o vertebra + -listhesis slipping | Forward slippage of one vertebra on another |
| Osteochondromatosis | oste/o bone + chondr/o cartilage + -oma + -osis | Condition of multiple bone-and-cartilage tumours |
| Thoracentesis | thorac/o chest + -centesis | Puncture of the pleural space to withdraw fluid |
| Cystourethrography | cyst/o bladder + urethr/o urethra + -graphy | Recording of the bladder and urethra |
6. Plural Forms
Latin and Greek plurals appear on requests and reports and are examinable.
| Singular ending | Plural ending | Example |
|---|---|---|
| -a | -ae | vertebra → vertebrae |
| -us | -i | bronchus → bronchi; alveolus → alveoli |
| -um | -a | atrium → atria; ilium → ilia |
| -is | -es | diagnosis → diagnoses; metastasis → metastases |
| -ix, -ex | -ices | apex → apices; appendix → appendices |
| -ma | -mata | carcinoma → carcinomata |
| -nx | -nges | phalanx → phalanges; meninx → meninges |
| -on | -a | ganglion → ganglia |
Test Your Knowledge
Apply the combining-vowel rule. Which pair of terms is spelled correctly?
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B
C
D
Test Your Knowledge
A request states that the patient underwent a colostomy last month. What procedure was performed?
A
B
C
D
Test Your Knowledge
Which statement correctly distinguishes the imaging suffixes?
A
B
C
D
Test Your Knowledge
Decode the term nephrolithotomy.
A
B
C
D