In his 1989 book Crazy English (Pocket Books, ISBN 0-671-68907-X), Richard Lederer calls such words and phrases "contronyms" and lists 41. This phenomenon has been a curiosity to users of language for

as long as there has been language and has many names
addad (Arabic) antilogy antiphrasis auto-antonymy didh (Arabic) enantiodromia (Greek) enantiosemy (Greek) enantiosis (Greek) gegensinn (German) Janus words l'shon hefech (Hebrew) mirror words oysterisms polarity self-antonymy turncoat words

Such words can be divided into homographs (same spelling) and homophones (same pronunciation).

A very short list of homophones
aural, oral = heard, spoken enumerable, innumerable = countable, uncountable erupt, irrupt = burst out, burst in eradicate, irradicate = pull up by the roots, root deeply fiance, fiancee = female betrothed, male betrothed raise, raze = erect, tear down reckless, wreckless = careless, careful succor, sucker = aid, hoodwink
A partial list of homographs
aboard = alongside, inside against = in the direction of and in contact with, in an opposite direction all downhill from here = things are going to get better, things are going to get worse aloha = hello, goodbye anabasis = military advance, military retreat anathema = something cursed, [rare? something consecrated to divine use anon = immediately [archaic? or soon, later anxious = full of mental distress because of apprehension of danger or misfortune [in effect, seeking to avoid? (We were anxious about the near by gunshots.), eager or looking forward to (until you returned, I was anxious to see you.) apparent = not clear or certain (for now, he is the apparent winner of the contest.), obvious (The solution to the problem was apparent to all.) apparent = seeming, clear ("heir apparent") argue = to try to prove by argument, [disputed? to argue against arsis = the unaccented or shorter part of a foot of verse; the accented or longer part of a foot of verse assume = to actually have (to assume office), to hope to have ("he assumed he would be elected.")

at the expense of = by sacrificing ("at the expense of accuracy"), disputed? by tolerating or introducing ("at the expense of inaccuracy")

aught = all, nothing ave = hail, farewell avocation = a hobby, a regular occupation and one could say it's a triple antagonym if you agree that the archaic meaning of "a distraction" is the opposite of working (even at a hobby) and if you agree that the obsolete meaning of "a calling away" takes you away from (the opposite of participating in) your hobbies, work, and even your distractions! awful = extremely unpleasant, ugly, awe-inspiring typically, a feeling of admiration? bad = of poor quality, [U.S. slang? good barrack = root or cheer, [Australian? jeer or heckle below par = good (in golf), bad (in health) bill = money, statement of money owed bimonthly/weekly = twice a month/week, once every two months/weeks bolt = to secure in place, to dart away bomb = [U.S. slang? a failure, [U.K. slang? a success bound = moving ("I was bound for Chicago"), unable to move ("I was bound to a post", or less literally, "I was bound to my desk") buckle = to hold together (e.g. buckle your belt), to fall apart (e.g., buckle under pressure) bull = a solemn edict or mandate, nonsense or worthless information by = spoken representation of multiplication sign ("3-by-3 matrix"), spoken representation of division sign ("d y by d x") cakewalk = easy task, intricate walk contest

cannot praise too highly = no praise is too high, cannot praise very highly

certain = definite, hard to specify ("I have a certain feeling.") charter = grant for pay, use for pay cheerio = hello, goodbye chine = ridge, [British dialect? ravine chuffed = [slang? pleased, [slang? annoyed cipher = zero, any number cite, citation = for doing good (such as military gallantry), for doing bad (such as from a traffic policeman) cleave = to separate, to join clip = cut apart, fasten together cognomen = first name, last name commencement = beginning, [disputed? conclusion ("high school commencement") comprise = to contain entirely ("the United States comprises 50 states"), to be included in ("The 50 states comprise the United States" ) consult = to ask the advice of, to give professional advice contingent = unpredictable, dependent on a known condition continue = proceed with, [US & Scottish legal usage? postpone cool = positive sense (cool web-sites), negative sense (cool reception) copemate = antagonist, partner could care less = (used as if it were synonymous with "could not care less"), one has no interest at all counterfeit = [archaic? a legitimate copy, a copy meant to deceive critical = opposed to ("critical of"), essential to ("critical to") custom = [noun? usual, [adjective? special cut = to get in ("cut line"), to get out ("cut class") deceptively <any adjective> = more <any adjective> than it looks, less ... dike = wall, ditch discursive = moving from topic to topic without order, proceeding coherently from topic to topic dispense with = distribute with, do without (We dispense with accuracy.) dispose of = to place in an orderly way, to get rid of divide by a half = to double, [disputed? to halve dollop = a large amount, [U.S.? a small amount down = hill, valley downhill = easy, progressively worse dress = put covering (usu. clothes) on, take covering (usu. skin) off dust = to remove dust, to apply dust (as in fingerprinting) edited = remaining after omissions have been made, disputed? omitted effectively = in effect (doing the equivalent of the action but not the real thing), with effect (doing the action and doing it well) Contrast "he is effectively lying" (colloquial?) with "he is lying effectively"? egregious = outstandingly bad, [archaic? distinguished enervate = to deplete the energy of, [disputed? to invigorate enjoin = to order someone to do something, to stop someone from doing something [such as in law by an injunction? factoid = speculation reported as fact, [disputed? unimportant fact fast = moving rapidly, unable to move ("I was held fast to my bed.") fearful = causing fear, being afraid finish = kill, perfect (at a finishing school) fireman = firefighter, fire-stoker (on train or ship) first-degree = most severe ("first-degree murder"), least severe ("first- degree burns")

fix = to restore to function (fixing the refrigerator), to make non-functional (fixing the dog)

flesh = add body matter, remove body matter flog = to criticize harshly, to promote aggressively for sure = certainly, [slang? certainly not fought with = fought on the same or opposite sides (The Finns fought with the Germans in WW II.) gale = a very strong wind, [archaic? a gentle breeze garble = to mix up, [archaic? to sort out garnish = to add to food, to subtract from wages gaum = to understand, to act stupid give out = to produce, to stop being produced go off = to become active, to become inactive good deal = [disputed? very much (expensive), very little (bargain) goods = [slang? good things, bad things ("I have the goods from the warehouse robbery, but I'm worried the police have the goods on me.") grade = an incline, level ("grade crossing") handicap = advantage (in golf), disadvantage help = to assist, to prevent ("I cannot help it if...") hoi polloi = the common people, disputed? the elite hold up = to support, to delay homely = [US? ugly, [UK? pleasant hysterical = being overwhelmed with fear in some cases?, being funny impregnable = invulnerable, [disputed? impregnatable impugnable = able to be impugned, [obsolete? impregnable incorporate = when a village is incorporated, it is formed, but when it is incorporated into a city, the village is destroyed inexistent = inherent, [obsolete? nonexistent infer = to take a hint, [disputed? to hint inside lane = [US? lane nearest center, [UK? lane nearest edge into = as a divisor of, [in India? multiplied by jake = [[disputed? uncouth (person), fine keep up = to continue to fall (rain), [disputed? to remain up kick off = begin, die last = just prior, final (my last book will be my last publication) lease = become lessor, become lessee left = departed from ("He left."), remaining ("He was left.") let = to permit, [archaic? to hinder license = liberty or permission to do something, undue or excessive freedom or liberty like never before = totally amateurish, with great skill (she's dancing like she's never danced before.) literally = actually, [disputed? figuratively (used before a metaphor) livid = discolored by bruising, pale look out for = be afraid of, anticipate lurch = run away, walk aimlessly mad = carried away by enthusiasm or desire, carried away by hatred or anger mark = write, read ("mark my words") mean = lowly ("rose from mean beginnings"), excellent ("plays a mean trombone") model = archetype, copy moot = debatable, [disputed? not worthy of debate mortal = receiver of death, giver of death ("He dealt a mortal blow.") mortar = glue together, blow apart mosey = run away, walk aimlessly nauseous = nauseating, [disputed? nauseated near miss = a hit close enough to achieve the effect, narrowly falling short of the objective nervy = showing calm courage, excitable note = promise to pay, money out = invisible (Turn the lights out.), visible (The moon is out.) out of = outside, inside ("work out of one's home") overlook = inspect, ignore oversight = care, error peep = to look quietly, to beep peer = noble, person of equal rank peruse = examine in detail, look over casually pitch = erect and fix firmly in place, throw away poke your head = make head poker, make head pokee policy = required activity without exception (university policy), an optional course of action (our government's policy regarding the economy) populate = to decimate the population (obsolete use), to increase the population practiced = [adjective? expert, [verb? inexpertly attempted prescribe = to lay down a rule, to become unenforceable presently = in a little while, [archaic? immediately priceless = have a very high value, having no market value

public school = [US? tax-supported school, [UK? endowed school

put = lay, throw put out = to generate ("candle puts out light"), to extinguish put up = set up, take down ("Put up your toys.") puzzle = to pose a problem, to solve a problem quaint = beautiful, odd qualified = competent, limited ("The dance was a qualified success.") quantum = very small ("quantum level"), [disputed? very large ("quantum leap") quiddity = an inessential feature, the essence quite = rather, completely ravel = to disentangle, [archaic? to tangle recover = hide away (cover again), bring out [hyphenated as re-cover? referent = something referred to, [disputed? something referring to refrain = [music? repeat a certain part, stop release = let go, hold on [hyphenated as re-lease? rent = to buy temporary use of, to sell temporary use of replace = take away (replace the worn carpet), put back (replace the papers in the file) repress = hold back, put forth (press again) [hyphenated as re-press? reprove = rebuke (reprove a colleague's work), support [hyphenated as re-prove? reservation = what you make when you know where you want to go, what you have when you're not sure if you want to go reside = to stay put, [slang? to change places (change teams) [hyphenated as re-side? resign = to quit a contract, to sign the contract again [hyphenated as re-sign? restive = refusing to move ("a restive horse"), restless reword = to repeat in different words, [archaic? to repeat in the same words riot = violent disorder, revelry ("It was a riot!") rival = an opponent, [archaic? a companion or associate rocky = firm, steadfast, tending to sway (e.g., a rocky shelf) root = to establish (The seed took root.), to remove entirely (Root out dissenters) rummage = thoroughly search, haphazardly search sanction = to approve of, [disputed? to punish sanguine = hopeful, [obsolete for "sanguinary"? murderous scan = to examine closely, to look over hastily scary = causing fright, easily scared screen = to show, to hide from view screwed = [slang? to be taken advantage of, to fool around and have fun secrete/d = to extrude, to hide seed = remove the seeds, distribute the seeds seeded = with seeds, without seeds set = bend, make unyielding; become established, come to an end (the era sets) shalom = hello, farewell shank of the evening = end of the evening, early part of the evening shop = to search with the intent to buy, to search with the intent to sell ("I shopped my manuscript to several publishers.") sick = unpleasant (a sick joke), [slang? wonderful siren = seductive sound, harsh sound skin = to cover with a skin, to remove outer covering or skin speak = express verbally, [disputed? express nonverbally stain = color, discolor stamp out = eliminate, produce in great quantities stipulate = request explicitly, agree to straight = not using drugs, [obsolete? under the influence of drugs strand = shore, [Scots? sea strike = to miss (baseball), to hit strike out = an ending ("The batter struck out."), a beginning ("I struck out on my own.") substitute = to put (something) in something else's place, [disputed? to replace (something) with something else tabby = a silk fabric, a rough kind of concrete table = [UK? to propose, [US? to set aside take = obtain, offer ("Models take good pictures.") take care of = look out for and nurture, [slang? get rid of or kill take fire = withstand fire, be ignited tell me about it = I want to know more, I already know temper = calmness, passion; harden (steel), soften (justice) terrific = extraordinarily good, causing terror thesis = [poetics? accented part, unaccented part think better of = to admire more, to be suspicious of through = [US? finished, [UK? connected (telephone) tilt = to incline toward, to charge against to a degree = [archaic? exceedingly, [disputed? to a certain extent to my knowledge = to my certain knowledge, as far as I know toast = popular ("the toast of the town"), [US slang? doomed transparent = obvious, invisible trim = to put things on ("trim a Christmas tree"), to take things off trip = to stumble, to move gracefully ("trip the light fantastic") tropics = area near equator, limits of this area turn it up = [US? increase volume, [UK? cease unbending = rigid, relaxing ("Learn to unbend.") undersexed = having a lower-than-normal sex drive, [disputed? sexually deprived unqualified = not qualified, very qualified ("He was an unqualified success.") vernacular = nonstandard speech, standard speech vital = lively, deadly watch out for = be afraid of, anticipate watershed = the divide between regions drained by different rivers, [disputed? the region drained by one river wear = to retain vitality, to deteriorate weather = to withstand (a storm), to wear away widdershins = counterclockwise, [in the southern hemisphere? clockwise wind up = to start (a watch), to stop (a speech) with = alongside, against (as in fighting) wraith = ghost of a dead person, apparition of a living person x = select (mark with an x), deselect (cross out) yuk = to express pleasant surprise (yak), to express unpleasant surprise (yuck) zing = to improve (by adding zest, interest or life to), to criticize

A very very short list of contranyms from other languages:

Chinese: louan = to govern well, to cause a disturbance

Dutch: ettelijk = many or much, little or few kooper = buyer, seller

French: La symetrie (symmetry), L'asymetrie (asymmetry) (homophones) defendre = to defend, to prohibit se marrer = to be bored, to enjoy one's self

German: versehen = to examine, to ignore Kontrahent = opponent, contractor

Greek: skhole = leisure, work due to leisure

Hebrew: hara = to create, to destroy nigash = approach, draw back

Russian: slovo = word, secret word or password [archaic?

Sahidic dialect of Coptic: ehrai = upwards, downwards

Swedish: maximera = set an upper limit to, make as large as possible

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