The HESI A2 Vocabulary section tests medical and general healthcare terminology. The good news: unlike anatomy, vocabulary is entirely learnable through targeted study. Here are the 100 terms our tutors have identified as the most frequently tested — covering prefixes, suffixes, and full medical terms.
💡 Study strategy: Learn word roots, prefixes, and suffixes — not just individual words. Understanding that tachy- means "fast" lets you decode tachycardia, tachypnea, and other unfamiliar terms you've never seen before.
Essential Prefixes
tachy-fast (tachycardia = fast heart rate)
brady-slow (bradycardia = slow heart rate)
hyper-above normal, excessive
hypo-below normal, deficient
poly-many (polydipsia = excessive thirst)
dys-painful, difficult, abnormal
a- / an-without, absent
anti-against
peri-around (pericardium = around the heart)
sub-under, below
intra-within (intravenous = within a vein)
inter-between (intercostal = between ribs)
trans-across, through
pre-before
post-after
hemi-half (hemiplegia = paralysis of one side)
Essential Suffixes
-itisinflammation (appendicitis)
-ectomysurgical removal
-oscopyvisual examination
-plastysurgical repair
-ologystudy of
-pathydisease of
-algiapain (myalgia = muscle pain)
-pneabreathing (dyspnea = difficult breathing)
-emiablood condition (anemia)
-uriaurine condition (hematuria = blood in urine)
-megalyenlargement (hepatomegaly)
-stenosisnarrowing of a passage
High-Frequency Clinical Terms
acutesudden onset, short duration
chroniclong-term, persistent
benignnot cancerous / not harmful
malignantcancerous, life-threatening
etiologycause of a disease
prognosisexpected outcome of a disease
contraindicationreason not to use a treatment
prophylaxispreventive treatment
palliativerelieving symptoms, not curing
idiopathiccause unknown
edemaswelling caused by fluid buildup
ischemiareduced blood flow to tissue
embolusblockage in a blood vessel
thrombusblood clot attached to vessel wall
pyrexiafever, elevated body temperature
diureticincreases urine production
analgesicpain-relieving medication
antipyreticfever-reducing medication
subcutaneousbelow the skin
intramuscularwithin the muscle
intravenouswithin a vein
NPOnothing by mouth
PRNas needed
statimmediately
How to Memorize These Efficiently
- Flashcards (physical or digital): Anki is free and uses spaced repetition — ideal for vocabulary
- Group by prefix/suffix: Learn all -itis words together, then move to -ectomy words
- Use words in sentences: "The patient had tachycardia" sticks better than memorizing "tachy = fast"
- Test yourself daily: 15 minutes of active recall beats 1 hour of passive reading
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