PREFIXES


With the meaning "not"


Prefixes (un-, in-, il-, ir-, and dis-) are often used to give adjectives (and some verbs and nouns) a negative meaning. Here are some common examples:

happy - unhappy
possible - impossible
correct - incorrect
like - dislike
legal - illegal
regular - irregular

UN- is used with many different words, e.g., unfriendly, unable, unbearable, unemployed, untidy

IM- is used before some words beginning with M or P, e.g., impolite, impatient


IL- is used before some words beginning with L, e.g., illegible


IR- is only used before some words beginning with R, e.g., irresponsible


DIS- is used before some adjectives, e.g., dishonest, and a few verbs, e.g., dislike, disagree


IN- is used before a limited number of words, e.g. invisible


Note: A prefix does not normally change word stress, e.g., happy / unhappy; possible / impossoble


Verb prefixes: un- and dis-


These prefixes have two meanings: they can have a negative meaning (as above), but they can also mean "the opposite of and action" or "to reverse an action". This meaning is used with certain verbs.

I locked the door when I left, but I lost the key, so I couldn´t unlock it when I got back.

I had to pack my suitcase very quickly, so when I unpacked at the hotel, most of my clothes looked terrible.

The plane appeared in the sky, then suddenly disappeared behind a cloud.

In the morning you get dressed; when you go to bed, you get undressed.


Other verb prefixes with specific meanings


re- (again)     My homework was terrible, so I had to redo it.
                     The shop closed down but will reopen next month.
                     I failed my exam but I can retake (or redo/resit) it next year.

over- (too much)     I think my boss is overdoing it at the moment. (= working too hard; also overwork)
                               I went to bed very late and I overslept this morning.
                               The shop assistant overcharged me.

mis- (badly or incorrectly)     I´m afraid I misunderstood what he said.
                                             Two of the students misread the first question.


(from the book English Vocabulary in Use) by Stuart Redman (Cambridge)


More prefixes:


un-, im-, il-, in-, ir-, dis-, non-, anti-, mis-, de-, counter-, co-, over-, out-, ex-, re-, under-, a-, hyper-, mal-. mono-, neo-


unattainable, non-existent, illegitimate, irresistible, inaccessble, unprepared, unaware, inexpensive, unconscious, intolerant, unlikely, improbable, dissatisfied, impatient, uncomplicated, unable, incapable, unenthusiastic, illegible, irrational, imperfect, non-resident


undo, disapprove, anticlockwise, misunderstand, disused, misused, unused, debriefing, miscast, unwrap, disembark, decentralize, anticlimax, disprove, declassify, disincentive, unconfirmed, dismount, undamaged, uncommon, unemployment, depersonalize, misfire, anticyclone


co-worker, overbalance, counterbalance, co-pilot, counterclain, co-author, overpriced, counterattack, overestimate, overreact, co-director, co-operate, overanxious, counter-espionage, overboard, oversimplify, coeducational, overdue, overdose


outpouring, ex-wife, outlast, outvote, redirect, undercooked, reoganize, ex-boyfriend, re-elect, undermine, outsize, redistribute, underexposure, outstay, reclaim, reunite, reassure, underclothes, underachiever, reintegrate


hyperactive, amoral, malnutrition, neo-Nazi, malformation, apolitical, hypersensitive, monosyllable, neoclassical, hypercritical, malfuncion, asymetrical, maladjusted, hypermarket, monotone


(from the book Recycling Advanced English - by Clare West (Georgian Press)


Some words with "out" and "over"


Outbid: to offer more money than another person in order to buy something, e.g., at an auction (sobrepujar num lance ou licitação)

Overbid: to offer to pay too much for something in relation to its value (oferecer mais do que vale; cobrir o lance ou oferta)

Overcharge: to charge too much money for something, usually deliberately (cobrar em excesso)

Outmanoeuvre:  to do better than an opponent, etc by acting more skillfully and cleverly (superar em estratégia, "passar a perna", vencer em habilidade)

Outnumber: to be greater in number than somebody/something (exceder em número)

Outrun: to develop faster than something, to run faster than somebody/spmething (correr mais que alguém, ultrapassar, exceder, deixar para trás)

Overrun: to continue beyond or exceed the time allowed or the expected cost (exceder, ultrapassar)

Outstrip: to become larger, more important, etc than somebody/something

Oversubscribe: if a company issues shares on the stock market and they are oversubscribed, the demand for shares is more than the number of shares available.

Overtake: to increase in number or amount so as to be more than something else

Outvote: to defeat somebody by gaining a larger number of votes (vencer por votos)


"Over" is used, among other things, to say that something is higher than something else.
"Out" is used, among other things, to say that something is not inside something, and to talk about leaving or move away from a place. To say that something goes beyond a particular level or number.