Here are some common prefixes that everyone should be familiar with.Â The definitions are from dictionary.com
un- (adjectives) not (ex. unfair; unfairly; unfairness; unfelt; unseen; unfitting; unformed; unheard-of; un-get-at-able)
Â Â Â Â Â Â (verbs) reversal of some action (ex. unbend; uncork; unfasten)
sub-Â â€œunder,â€ â€œbelow,â€ â€œbeneathâ€ (subalpine; substratum), â€œslightly,â€ â€œimperfectly,â€ â€œnearlyâ€ (subcolumnar; subtropical), â€œsecondary,â€ â€œsubordinateâ€ (subcommittee; subplot)
mid- middle (ex. midday, midpoint, midfield)
re- “againâ€ or â€œagain and againâ€ to indicate repetition, or with the meaning â€œbackâ€ or â€œbackwardâ€ to indicate withdrawal or backward motion: regenerate; refurbish; retype; retrace; revert
dis- a Latin prefix meaning â€œapart,â€ â€œasunder,â€ â€œaway,â€ â€œutterly,â€ or having a privative, negative, or reversing force (see de-, un–2); used freely, esp. with these latter senses, as an English formative: disability; disaffirm; disbar; disbelief; discontent; dishearten; dislike; disown.
non- a prefix meaning â€œnot,â€ freely used as an English formative, usually with a simple negative force as implying mere negation or absence of something (rather than the opposite or reverse of it, as often expressed by un-1): nonadherence; noninterference; nonpayment; nonprofessional.
over- a prefixal use of over, preposition, adverb, or adjective, occurring in various senses in compounds (overboard; overcoat; overhang; overlap; overlord; overrun; overthrow), and especially employed, with the sense of â€œover the limit,â€ â€œto excess,â€ â€œtoo much,â€ â€œtoo,â€ to form verbs, adjectives, adverbs, and nouns (overact; overcapitalize; overcrowd; overfull; overmuch; oversupply; overweight), and many others, mostly self-explanatory: a hyphen, which is commonly absent from old or well-established formations, is sometimes used in new coinages or in any words whose component parts it may be desirable to set off distinctly.
pre- a prefix occurring originally in loanwords from Latin, where it meant â€œbeforeâ€ (preclude; prevent); applied freely as a prefix, with the meanings â€œprior to,â€ â€œin advance of,â€ â€œearly,â€ â€œbeforehand,â€ â€œbefore,â€ â€œin front of,â€ and with other figurative meanings (preschool; prewar; prepay: preoral; prefrontal).
im-var. of in-2 before b, m, p: imbrute; immigrate; impassion.
in- a prefix of Latin origin, corresponding to English un-, having a negative or privative force, freely used as an English formative, esp. of adjectives and their derivatives and of nouns (inattention; indefensible; inexpensive; inorganic; invariable). It assumes the same phonetic phases as in- 2 (impartial; immeasurable; illiterate; irregular, etc.). In French, it became en- and thus occurs unfelt in such words as enemy (French ennemi, Latin inimicus, lit., not friendly).