Why Medical Word Parts Are Your Secret Weapon
Here's a fact that changes everything about HESI A2 Vocabulary prep: you don't need to memorize thousands of individual medical terms. Instead, you need to master roughly 150 word parts — prefixes, suffixes, and root words — that combine to form virtually every medical term you'll encounter on the exam.
Think of it like learning a code. Once you know that cardio- means heart, -itis means inflammation, and myo- means muscle, you can instantly decode myocarditis (inflammation of the heart muscle) — even if you've never seen the word before.
This guide gives you every word part you need for the HESI A2, organized by category with examples and memory tricks.
How the HESI A2 Tests Vocabulary
The Vocabulary and General Knowledge section typically includes 55 questions. You'll see questions like:
- "What is the meaning of tachycardia?" (rapid heart rate)
- "The prefix hyper- means:" (excessive/above normal)
- "A patient with dyspnea is experiencing difficulty with:" (breathing)
- "The suffix -ectomy indicates:" (surgical removal)
Knowing word parts lets you answer these confidently — even for terms you haven't specifically studied.
Essential Prefixes (Direction, Location & Position)
Above, Below & Around
- epi- = upon, above → epidermis (outer layer of skin)
- hypo- = below, under → hypodermic (under the skin)
- hyper- = above, excessive → hypertension (high blood pressure)
- sub- = under, below → sublingual (under the tongue)
- supra- = above → suprarenal (above the kidney)
- peri- = around → pericardium (membrane around the heart)
- circum- = around → circumduction (circular movement)
Inside, Outside & Between
- endo- = within → endoscopy (looking inside)
- exo- = outside → exocrine (secreting externally)
- extra- = outside, beyond → extracellular (outside the cell)
- inter- = between → intercostal (between the ribs)
- intra- = within → intravenous (within a vein)
- trans- = across → transfusion (transfer across)
- retro- = behind, backward → retroperitoneal (behind the peritoneum)
Essential Prefixes (Size, Number & Quantity)
Size and Degree
- macro- = large → macrocyte (large cell)
- micro- = small → microscope (instrument for viewing small things)
- mega-/megalo- = large, enlarged → megacolon (enlarged colon)
- poly- = many → polydipsia (excessive thirst)
- oligo- = few, scanty → oliguria (low urine output)
- pan- = all → pandemic (affecting all people)
Numbers
- uni-/mono- = one → unilateral (one side)
- bi-/di- = two → bilateral (two sides)
- tri- = three → tricuspid (three cusps)
- quad-/tetra- = four → quadriplegia (paralysis of four limbs)
- multi- = many → multipara (woman who has given birth multiple times)
- hemi-/semi- = half → hemiplegia (paralysis of half the body)
Essential Prefixes (Condition & Status)
- a-/an- = without, absence of → anemia (without enough blood), apnea (without breathing)
- anti- = against → antibiotic (against bacteria)
- auto- = self → autoimmune (immune system attacks self)
- brady- = slow → bradycardia (slow heart rate)
- tachy- = fast, rapid → tachypnea (rapid breathing)
- dys- = difficult, painful, abnormal → dysphagia (difficulty swallowing)
- eu- = good, normal → eupnea (normal breathing)
- mal- = bad, abnormal → malnutrition (bad nutrition)
- neo- = new → neoplasm (new growth/tumor)
- pseudo- = false → pseudocyst (false cyst)
- pre- = before → prenatal (before birth)
- post- = after → postoperative (after surgery)
Essential Root Words (Body Systems)
Cardiovascular System
- cardi/o = heart → cardiology
- angi/o, vas/o = vessel → angioplasty, vascular
- hem/o, hemat/o = blood → hemorrhage, hematology
- ven/o, phleb/o = vein → venous, phlebotomy
- arteri/o = artery → arteriosclerosis
- thromb/o = clot → thrombosis
Respiratory System
- pulmon/o, pneum/o = lung → pulmonary, pneumonia
- bronch/o = bronchus → bronchitis
- trache/o = trachea → tracheotomy
- laryng/o = larynx → laryngitis
- pharyng/o = pharynx → pharyngitis
- nas/o, rhin/o = nose → nasal, rhinoplasty
Digestive System
- gastr/o = stomach → gastritis
- hepat/o = liver → hepatitis
- enter/o = intestine → enteritis
- col/o = colon → colitis
- cholecyst/o = gallbladder → cholecystectomy
- pancreat/o = pancreas → pancreatitis
- esophag/o = esophagus → esophageal
Musculoskeletal System
- oste/o = bone → osteoporosis
- arthr/o = joint → arthritis
- my/o, muscul/o = muscle → myalgia, muscular
- chondr/o = cartilage → chondritis
- tend/o, tendin/o = tendon → tendinitis
Nervous System
- neur/o = nerve → neurology
- cerebr/o = brain (cerebrum) → cerebrovascular
- encephal/o = brain → encephalitis
- mening/o = meninges → meningitis
- psych/o = mind → psychology
Urinary System
- ren/o, nephr/o = kidney → renal, nephritis
- cyst/o = bladder → cystitis
- ur/o = urine → urology
- ureter/o = ureter → ureteritis
- urethr/o = urethra → urethritis
Integumentary & Sensory
- derm/o, dermat/o = skin → dermatology
- ophthalm/o, ocul/o = eye → ophthalmology, ocular
- ot/o = ear → otitis
- or/o, stomat/o = mouth → oral, stomatitis
Essential Suffixes (Conditions & Diseases)
- -itis = inflammation → appendicitis (inflammation of the appendix)
- -osis = abnormal condition → cyanosis (blue discoloration)
- -emia = blood condition → anemia (low red blood cells)
- -oma = tumor → carcinoma (cancerous tumor)
- -algia, -dynia = pain → myalgia (muscle pain), pleurodynia (chest wall pain)
- -pathy = disease → neuropathy (nerve disease)
- -plegia = paralysis → paraplegia (lower body paralysis)
- -rrhage, -rrhagia = excessive flow/bleeding → hemorrhage
- -penia = deficiency → thrombocytopenia (low platelets)
- -stenosis = narrowing → arteriostenosis (narrowing of arteries)
- -sclerosis = hardening → atherosclerosis (hardening of arteries)
- -megaly = enlargement → cardiomegaly (enlarged heart)
- -malacia = softening → osteomalacia (softening of bones)
Essential Suffixes (Procedures & Instruments)
- -ectomy = surgical removal → appendectomy (removal of appendix)
- -otomy, -tomy = incision, cutting into → tracheotomy (incision into trachea)
- -ostomy = creating an opening → colostomy (opening in colon)
- -plasty = surgical repair → rhinoplasty (nose repair)
- -pexy = surgical fixation → nephropexy (fixation of kidney)
- -rrhaphy = suturing → herniorrhaphy (suturing a hernia)
- -centesis = puncture to remove fluid → amniocentesis
- -scopy = visual examination → endoscopy (looking inside)
- -scope = instrument for viewing → stethoscope
- -graph = recording instrument → electrocardiograph
- -gram = the record itself → electrocardiogram
- -meter = measuring instrument → thermometer
Essential Suffixes (Descriptions & States)
- -ic, -al, -ous, -ar = pertaining to → cardiac (pertaining to heart), renal (pertaining to kidney)
- -logy = study of → cardiology (study of the heart)
- -logist = specialist → neurologist (nerve specialist)
- -genesis = origin, formation → pathogenesis (origin of disease)
- -lysis = breakdown, destruction → hemolysis (breakdown of blood cells)
- -stasis = stopping, controlling → hemostasis (stopping bleeding)
- -trophy = nourishment, development → atrophy (wasting away), hypertrophy (overgrowth)
- -philia = attraction to → hemophilia (tendency to bleed)
- -phobia = fear of → claustrophobia
Power Combos: Decoding Complex Terms
Now let's put it all together. Practice breaking down these terms you might see on the HESI A2:
- Electrocardiogram = electr/o (electrical) + cardi/o (heart) + -gram (record) → electrical recording of the heart
- Thrombocytopenia = thromb/o (clot) + cyt/o (cell) + -penia (deficiency) → deficiency of clotting cells (platelets)
- Cholecystectomy = cholecyst/o (gallbladder) + -ectomy (surgical removal) → surgical removal of the gallbladder
- Polyneuropathy = poly- (many) + neur/o (nerve) + -pathy (disease) → disease of many nerves
- Endotracheal = endo- (within) + trache/o (trachea) + -al (pertaining to) → pertaining to within the trachea
- Hyperglycemia = hyper- (excessive) + glyc/o (sugar) + -emia (blood condition) → excessive sugar in the blood
- Tachypnea = tachy- (fast) + -pnea (breathing) → rapid breathing
- Osteoarthritis = oste/o (bone) + arthr/o (joint) + -itis (inflammation) → inflammation of bone and joint
5 Memory Tricks for Word Parts
1. The Story Method
Create vivid stories: "Brady the snail has bradycardia — his heart beats as slow as he moves." The sillier the story, the better it sticks.
2. Opposite Pairs
Always learn opposites together:
- tachy- (fast) ↔ brady- (slow)
- hyper- (above) ↔ hypo- (below)
- macro- (large) ↔ micro- (small)
- endo- (within) ↔ exo- (outside)
3. Body System Groups
Study all word parts for one body system in a single session. When you learn cardi/o, also learn angi/o, hem/o, ven/o, and arteri/o in the same sitting.
4. Real-World Connections
Connect word parts to things you already know: "A microscope looks at micro (small) things, so micro- means small."
5. Daily Decode Practice
Pick 5 random medical terms each day and break them into parts. This builds the habit of analysis that will serve you on exam day.
Quick-Reference Study Strategy
Here's the most efficient way to study this cheat sheet:
- Week 1: Focus on the 30 most common prefixes. Use flashcards for daily review.
- Week 2: Add root words organized by body system (cardiovascular → respiratory → digestive).
- Week 3: Master all suffixes, especially condition (-itis, -osis, -emia) and procedure (-ectomy, -otomy, -scopy) groups.
- Week 4: Practice decoding complex terms and take vocabulary practice quizzes.
By spending just 20 minutes per day with these word parts, you'll build a vocabulary foundation that makes the HESI A2 Vocabulary section feel manageable — even enjoyable.