Lesson 1: Medical Terminology Prefixes

a- (an- before vowel or h)

without, lacking, deficient

anti- (ant- before a vowel or h)

against, opposed to, preventing, relieving

di- (rarely dis-)

two, twice, double

dys-

difficult, painful, defective, abnormal

ec (ex- before a vowel)

out of, away from

ecto- (ect- before a vowel)

outside of

en- (em- before b, m, and p)

in, into, within

endo-, ento- (end-, ent- before a vowel or h)

within

epi- (ep- before a vowel or h)

upon, over, above

exo-

outside, from the outside, toward the outside

hemi-

half, partial, (often) one side on the body

hyper-

over, above, excessive, beyond normal

hypo- (hyp- before a vowel or h)

under, deficient, below normal

mono- (mon- before a vowel or h)

one, single

peri-

around, surrounding

syn- (sym- before b, p, and m; the n assimilates or is dropped before s)

together, with, joined