1.1 Medical Terminology
Key Takeaways
- Medical terms follow a consistent structure: prefix + root word + combining vowel + suffix, enabling interpretation of unfamiliar clinical terms
- Common prefixes include hyper- (excessive), hypo- (deficient), tachy- (fast), brady- (slow), poly- (many), and dys- (difficult/painful)
- Root words identify the body part: cardi/o (heart), pulmon/o (lung), gastr/o (stomach), hepat/o (liver), nephr/o (kidney), oste/o (bone)
- Common suffixes indicate conditions or procedures: -itis (inflammation), -ectomy (surgical removal), -osis (abnormal condition), -algia (pain)
- The combining vowel (usually "o") connects root words to suffixes beginning with consonants but is dropped before vowel-starting suffixes
- Abbreviations like PRN (as needed), STAT (immediately), NPO (nothing by mouth), and BID (twice daily) are used daily in clinical settings
Last updated: March 2026
Medical Terminology
Medical terminology is the standardized language used throughout healthcare. Understanding how medical terms are constructed allows you to decode unfamiliar words, accurately document patient information, and communicate effectively with physicians, nurses, and other healthcare professionals.
Word Building: The Four Components
Every medical term is built from up to four components:
| Component | Position | Function | Example |
|---|---|---|---|
| Prefix | Beginning | Modifies meaning | hyper- (excessive) |
| Root word | Middle/core | Identifies body part or condition | cardi (heart) |
| Combining vowel | Between root and suffix | Connects components (usually "o") | cardi/o/myopathy |
| Suffix | End | Indicates procedure, condition, or disease | -itis (inflammation) |
Rules for combining vowels:
- Use the combining vowel when the suffix starts with a consonant: cardi/o/logy
- Drop the combining vowel when the suffix starts with a vowel: cardi/itis (not cardi/o/itis)
- Always use the combining vowel between two root words: gastr/o/enter/itis
Essential Prefixes
| Prefix | Meaning | Example | Definition |
|---|---|---|---|
| a-, an- | Without, absence of | Apnea | Without breathing |
| hyper- | Above, excessive | Hypertension | High blood pressure |
| hypo- | Below, deficient | Hypoglycemia | Low blood sugar |
| tachy- | Fast, rapid | Tachycardia | Fast heart rate (>100 bpm) |
| brady- | Slow | Bradycardia | Slow heart rate (<60 bpm) |
| poly- | Many, excessive | Polyuria | Excessive urination |
| oligo- | Few, scanty | Oliguria | Decreased urine output |
| dys- | Difficult, painful | Dyspnea | Difficult breathing |
| anti- | Against | Antibiotic | Against bacteria |
| hemi- | Half | Hemiplegia | Paralysis of one side |
| peri- | Around | Pericardium | Membrane around the heart |
| sub- | Below, under | Subcutaneous | Under the skin |
| supra- | Above | Suprapubic | Above the pubic bone |
| inter- | Between | Intercostal | Between the ribs |
| intra- | Within | Intravenous | Within a vein |
| post- | After | Postoperative | After surgery |
| pre- | Before | Prenatal | Before birth |
| endo- | Within | Endoscopy | Looking within |
| epi- | Upon, above | Epigastric | Upon the stomach region |
| retro- | Behind, backward | Retroperitoneal | Behind the peritoneum |
Essential Root Words
| Root | Meaning | Example |
|---|---|---|
| cardi/o | Heart | Cardiology |
| pulmon/o | Lung | Pulmonary |
| gastr/o | Stomach | Gastritis |
| hepat/o | Liver | Hepatitis |
| nephr/o, ren/o | Kidney | Nephrology, renal |
| oste/o | Bone | Osteoporosis |
| neur/o | Nerve | Neurology |
| derm/o, dermat/o | Skin | Dermatology |
| hem/o, hemat/o | Blood | Hematology |
| arthr/o | Joint | Arthritis |
| my/o | Muscle | Myocardial |
| cyst/o | Bladder | Cystitis |
| encephal/o | Brain | Encephalitis |
| enter/o | Intestine | Enteritis |
| pneum/o | Lung, air | Pneumonia |
| col/o | Colon | Colitis |
| cyt/o | Cell | Cytology |
| lith/o | Stone | Lithotripsy |
| path/o | Disease | Pathology |
| thromb/o | Clot | Thrombosis |
Essential Suffixes
| Suffix | Meaning | Example |
|---|---|---|
| -itis | Inflammation | Appendicitis |
| -ectomy | Surgical removal | Appendectomy |
| -otomy | Cutting into | Tracheotomy |
| -ostomy | Creating a new opening | Colostomy |
| -osis | Abnormal condition | Cyanosis |
| -ology | Study of | Cardiology |
| -algia | Pain | Neuralgia |
| -emia | Blood condition | Anemia |
| -pathy | Disease | Neuropathy |
| -scope | Instrument for viewing | Stethoscope |
| -scopy | Process of viewing | Endoscopy |
| -plasty | Surgical repair | Rhinoplasty |
| -megaly | Enlargement | Cardiomegaly |
| -penia | Deficiency | Thrombocytopenia |
| -rrhage, -rrhagia | Excessive flow/bleeding | Hemorrhage |
| -rrhaphy | Suturing | Herniorrhaphy |
| -rrhea | Flow, discharge | Diarrhea |
| -centesis | Surgical puncture to aspirate | Thoracentesis |
| -graphy | Process of recording | Radiography |
| -gram | Record or image | Electrocardiogram |
Common Medical Abbreviations for CCMAs
Medical assistants must know these abbreviations used in clinical orders, documentation, and communication:
Frequency Abbreviations
| Abbreviation | Meaning |
|---|---|
| PRN | As needed (pro re nata) |
| STAT | Immediately |
| BID | Twice daily (bis in die) |
| TID | Three times daily (ter in die) |
| QID | Four times daily (quater in die) |
| QD | Every day (quaque die) |
| QOD | Every other day |
| AC | Before meals (ante cibum) |
| PC | After meals (post cibum) |
| HS | At bedtime (hora somni) |
Route Abbreviations
| Abbreviation | Meaning |
|---|---|
| PO | By mouth (per os) |
| IM | Intramuscular |
| IV | Intravenous |
| SubQ / SQ | Subcutaneous |
| ID | Intradermal |
| SL | Sublingual (under the tongue) |
| PR | Per rectum |
| TOP | Topical |
Clinical Abbreviations
| Abbreviation | Meaning |
|---|---|
| NPO | Nothing by mouth (nil per os) |
| VS | Vital signs |
| BP | Blood pressure |
| HR | Heart rate |
| RR | Respiratory rate |
| T | Temperature |
| Ht | Height |
| Wt | Weight |
| BMI | Body mass index |
| SOB | Shortness of breath |
| CC | Chief complaint |
| HPI | History of present illness |
| PMH | Past medical history |
| ROS | Review of systems |
| Dx | Diagnosis |
| Tx | Treatment |
| Rx | Prescription |
| Hx | History |
| Sx | Symptoms |
| NKA / NKDA | No known allergies / No known drug allergies |
| UA | Urinalysis |
| CBC | Complete blood count |
| BMP / CMP | Basic / Comprehensive metabolic panel |
| Hgb / Hb | Hemoglobin |
| Hct | Hematocrit |
| WBC | White blood cell count |
| FBS / FBG | Fasting blood sugar / Fasting blood glucose |
Do Not Use Abbreviations (Joint Commission)
The Joint Commission maintains a "Do Not Use" list of abbreviations that are prone to misinterpretation:
| Do NOT Use | Problem | Use Instead |
|---|---|---|
| U (for units) | Mistaken for "0" or "4" | Write "units" |
| IU (international units) | Mistaken for "IV" | Write "international units" |
| Q.D. / Q.O.D. | Mistaken for each other | Write "daily" / "every other day" |
| MS / MSO4 / MgSO4 | MS confused with morphine/magnesium | Write "morphine sulfate" or "magnesium sulfate" |
| Trailing zero (e.g., 1.0 mg) | Decimal point missed → 10 mg | Write "1 mg" |
| Lack of leading zero (e.g., .5 mg) | Decimal point missed → 5 mg | Write "0.5 mg" |
Test Your Knowledge
The medical term "tachycardia" is built from which components?
A
B
C
D
Test Your Knowledge
What does the abbreviation "NPO" mean?
A
B
C
D
Test Your Knowledge
According to the Joint Commission "Do Not Use" list, which abbreviation should NOT be used in medical documentation?
A
B
C
D
Test Your KnowledgeFill in the Blank
The suffix "-ectomy" means surgical _____ of an organ or structure.
Type your answer below