A List of 35 Common Prefixes in English

Vocabulary Building: Common Prefixes With Definitions and Examples

Unicycle
The prefix uni- means "one".
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 (in some browsers, just below the ads) defines and illustrates 35 common prefixes.

Common Prefixes

PrefixMeaningExamples
a-, an-without, lack of, not amoral, acellular, abyss, achromatic, anhydrous 
ante-before, earlier, in front of antecedent, antedate, antemeridian, anterior  
anti-against, opposite ofanticlimax. antiaircraft, antiseptic, antibody
auto-self, sameautopilot, autobiography, automobile, autofocus
circum-around, aboutcircumvent, circumnavigate, circumscribe
co-with, togethercopilot, coworker, coexist, coauthor
com-, con-together, withcompanion, commingle, contact, concentrate
contra-, contro-against, oppositecontradict, contrast, contrary, controversy 
de-down, off, away fromdevalue, deactivate, debug, degrade, deduce
dis-not, apart, awaydisappear, disagreeable, disbar, dissect
en-put into, cover withenclose, entangle, enslave, encase 
ex-out of, from, formerextract, exhale, excavate, ex-president 
extra-beyond, outside, more than extracurricular, extramarital, extravagant
hetero-different, otherheterosexual, heterodox, heterogeneous
homo-, homeo-same, alikehomonym, homophone, homeostasis, homosexual
hyper-over, more, beyondhyperactive, hypersensitive, hypercritical
il-, im-, in-, ir-not, withoutillegal, immoral, inconsiderate, irresponsible
in-in, intoinsert, inspection, infiltrate
inter-between, amongintersect, interstellar, intervene, interpenetrate
intra-, intro-within, insideintravenous, intragalactic, introvert  
macro-large, prominentmacroeconomics, macrostructure, macrocosm
micro-very smallmicroscope, microcosm, microbe
mono-one, single, alonemonocle, monologue, monogamy, monotony  
non-not, withoutnonentity, nonaggressive, nonessential, nonfiction
omni-all, everyomniscient, omnivorous, omniscient, omnidirectional 
post-after, behindpostmortem, posterior, postscript, postoperative
pre-, pro-before, forwardprecede, predict, project, prologue
sub-under, lowersubmarine, subsidiary, substandard
sym-, syn-same time, togethersymmetry, symposium, synchronize, synapse 
trans-across, beyond, throughtransmit, transaction, translation, transfer
tri-three, every thirdtricycle, trimester, triangle, triathlon
un-not, lacking, opposite ofunfinished, unskilled, ungraceful, unfriendly
uni-one, singleunicorn, unicellular, unicycle, unilateral
   

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