A List of 35 Common Prefixes in English

If you were a prefix, you could change the same word in different ways.
You could make a cycle a unicycle, a bicycle, or a tricycle.
_{(Marcie Aboff and Sara Gray, If You Were a Prefix. Picture Window Books, 2008)}

A prefix is a letter or a group of letters attached to the beginning of a word (or word root) that partly indicates its meaning. For example, the word prefix itself begins with the prefix pre-, which generally means "before" or "in front of."

Many of today's English words contain prefixes from Greek or Latin. Understanding the meanings of the most common prefixes can help us deduce the meanings of new words that we run across in our reading.

Still, we do need to be careful: the same prefix may be spelled in more than one way (pre- and pro-, for instance), and some prefixes (such as in-) have more than one meaning (in this case, "not" and "into"). Even so, being able to recognize prefixes can help us build our vocabularies.

The following table defines and illustrates 35 common prefixes.

Common Prefixes

Prefix	Meaning	Examples
a-, an-	without, lack of, not	amoral, acellular, abyss, achromatic, anhydrous
ante-	before, earlier, in front of	antecedent, antedate, antemeridian, anterior
anti-	against, opposite of	anticlimax. antiaircraft, antiseptic, antibody
auto-	self, same	autopilot, autobiography, automobile, autofocus
circum-	around, about	circumvent, circumnavigate, circumscribe
co-	with, together	copilot, coworker, coexist, coauthor
com-, con-	together, with	companion, commingle, contact, concentrate
contra-, contro-	against, opposite	contradict, contrast, contrary, controversy
de-	down, off, away from	devalue, deactivate, debug, degrade, deduce
dis-	not, apart, away	disappear, disagreeable, disbar, dissect
en-	put into, cover with	enclose, entangle, enslave, encase
ex-	out of, from, former	extract, exhale, excavate, ex-president
extra-	beyond, outside, more than	extracurricular, extramarital, extravagant
hetero-	different, other	heterosexual, heterodox, heterogeneous
homo-, homeo-	same, alike	homonym, homophone, homeostasis, homosexual
hyper-	over, more, beyond	hyperactive, hypersensitive, hypercritical
il-, im-, in-, ir-	not, without	illegal, immoral, inconsiderate, irresponsible
in-	in, into	insert, inspection, infiltrate
inter-	between, among	intersect, interstellar, intervene, interpenetrate
intra-, intro-	within, inside	intravenous, intragalactic, introvert
macro-	large, prominent	macroeconomics, macrostructure, macrocosm
micro-	very small	microscope, microcosm, microbe
mono-	one, single, alone	monocle, monologue, monogamy, monotony
non-	not, without	nonentity, nonaggressive, nonessential, nonfiction
omni-	all, every	omniscient, omnivorous, omniscient, omnidirectional
post-	after, behind	postmortem, posterior, postscript, postoperative
pre-, pro-	before, forward	precede, predict, project, prologue
sub-	under, lower	submarine, subsidiary, substandard
sym-, syn-	same time, together	symmetry, symposium, synchronize, synapse
trans-	across, beyond, through	transmit, transaction, translation, transfer
tri-	three, every third	tricycle, trimester, triangle, triathlon
un-	not, lacking, opposite of	unfinished, unskilled, ungraceful, unfriendly
uni-	one, single	unicorn, unicellular, unicycle, unilateral