A prefix is one or more letters added before a base word to change its meaning. Prefixes have different functions. They may make the word negative (-un, in), by showing repetition (-re), or by showing support (-pro).
Prefixes are mostly used to shorten phrases. For example, if you want to say that someone is “eating too much“, you can simply say that they are “overeating“.
Here is a list of prefixes from a-z and their meaning and examples.
| Prefix | Meaning | Example |
| ab | away, from | abstract, abort, abrupt |
| a | not or without, a state of being | atypical, amoral, anew |
| ad | to, toward, near | adjust, adapt, adverb |
| ambi | both | ambivalent, ambilateral |
| ante- | before | anteroom, antechoir |
| anti- | against, opposing | antibiotic, antibacterial |
| arch | chief, most important | archenemy, archbishop |
| a | at, in, on, to | awake |
| at | to, toward | attend |
| auto | self | automatic, autobiography |
| be | cause to be | bespoke, belittle |
| bene | good | benefactor, benediction |
| bi | two, twice | bicycle, billingual |
| circum- | around | circumference, circuit |
| co | with, together | collude, coalition |
| con | jointly | connect, consensus |
| contra | against | contraindicate, contraceptive |
| counter | opposite | counteract, counterbalance |
| co- | with | co-author, co-parent |
| deca | ten | decagon, decagram |
| demi | half | demibillionaire, demivoice |
| de- | off, down, away from | descend, deactivate, declog |
| dia | through, across | diagonal, diagram |
| dis- | opposite of, not | disadvantage, discredit |
| di | two | dilemma |
| dys | bad, abnormal | dyslexia |
| em- | cause to | embitter, empower |
| em-, en- | cause to, put into | enlighten, embody |
| en- | to cause, provide | ensure |
| endo | internal | endoscopy |
| epi- | upon, close to, after | epidemic, epilogue |
| equi | equal | equilibrium |
| ethno | race, nation | ethnocentric |
| ex- | former, out of | ex-wife, exclude |
| extra- | outside, beyond | extramarital, extracurricular |
| fore- | before | forefather, foresee |
| homo- | same | homonym, homosexual |
| hyper- | beyond, more than, more than normal | hypersensitive, hyperbole |
| im-,-in | in | improper, influence |
| il-, im-, in-, ir- | not | illogical, impossible, inappropriate, irrational |
| infra- | beneath, below | infrastructure, infrahuman |
| im-, in- | into | inject, imbibe |
| inter-, intra- | between | interact, intravenous |
| macro- | large | macrolanguage, macrohistory |
| micro- | small | microchip, microorganism |
| mid- | middle | midterm, midpoint |
| mis- | wrongly | misuse, mismanage |
| mono- | one, singular | monologue, monopoly |
| non- | not, without | nonfiction, nonpayment |
| omni- | all, every | omnipresent, omniscience |
| over- | over | overrule, overkill |
| para- | beside, closely related | paragraph, paradigm |
| post- | after | postgame, postseason |
| pre- | before | prenatal, prenuptial |
| re- | again | restart, relive |
| semi- | half | semicircle, semiformal |
| sub- | under | submarine, subordinate, subtitle |
| therm- | heat | thermal, thermonuclear |
| trans- | across, beyond | translucent, transparent |
| tri- | three | tristate, triathlon, tricolor |
| under- | under | underpay, undergo |
| un- | not | unable, uncommon, unhappy |
| uni- | one | unicameral, unison |
Tips:
When to use hyphens with prefixes:
a. Prefix with a proper noun except for the word “transatlantic“, the only word that does not follow this rule on proper nouns.
| pro-China protesters |
| trans-American flights |
b. If the word with the prefix already exists, use a hyphen.
| resign = voluntarily leave a job or other position |
| re-sign = sign (a document) again |
c. all-, ex– (former), and self–
| all-knowing |
| ex-husband |
| self-care |
Only use a hyphen when the meaning of ex- is “former” or “in the past.”
Note:
The prefix “extra” does not need a hyphen if it means “outside of“.
| extraordinary |
| extravagant |