What words are their own antonym? by Mark Israel Richard Lederer, in Crazy English (Pocket Books, 1989, ISBN 0-671-68907-X), calls these "contronyms". They can be divided into homographs (same spelling) and homophones (same pronunciation). The homographs include: anabasis = military advance, military retreat anathema = something cursed, [rare] something consecrated to divine use 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 at the expense of = by sacrificing ("at the expense of accuracy"), [disputed] by tolerating or introducing ("at the expense of inaccuracy") aught = all, nothing bad = of poor quality, [U.S. slang] good bill = invoice, money bolt = to secure, to run away bomb = [U.S. slang] a failure, [U.K. slang] a success buckle = to fasten, to fall apart ("buildings buckle at an earthquake") by = spoken representation of multiplication sign ("3-by-3 matrix"), spoken representation of division sign ("d y by d x") cannot praise too highly = no praise is too high, cannot praise very highly certain = definite, unspecified chine = ridge, [British dialect] ravine chuffed = pleased, annoyed cite = single out for praise ("cited for bravery"), single out for blame ("citation from the Buildings Dept.") cleave = to separate, to adhere clip = to fasten, to detach commencement = beginning, conclusion ("high school commencement") comprise = to contain, [disputed] to compose consult = to ask the advice of, to give professional advice contingent = unpredictable, dependent on a known condition continue = to keep on doing, [Scots and U.S. law] to adjourn copemate = antagonist, partner critical = opposed to ("critical of"), essential to ("critical to") custom = usual, special deceptively shallow = shallower than it looks, deeper than it looks dike = wall, ditch discursive = moving from topic to topic without order, proceeding coherently from topic to topic divide by a half = to double, [disputed] to halve dollop = a large amount, [U.S.] a small amount dress = to put items on, to remove items from ("dress the chicken") dust = to remove fine particles, to add fine particles edited = remaining after omissions have been made, [disputed] omitted egregious = outstandingly bad, [archaic] distinguished enervate = to deplete the energy of, [disputed] to invigorate enjoin = to prescribe, [law] to prohibit factoid = speculation reported as fact, [disputed] unimportant fact fast = rapid, unmoving fireman = firefighter, fire-stoker (on train or ship) first-degree = most severe ("first-degree murder"), least severe ("first-degree burns") fix = to restore, to castrate flog = to criticize harshly, to promote aggressively gale = a very strong wind, [archaic] a gentle breeze garble = to mix up, [archaic] to sort out garnish = to enhance (food), to curtail (wages) give out = to produce, to stop being produced go off = to become active, to become inactive 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 impregnable = invulnerable, [disputed] impregnatable inexistent = inherent, [obsolete] nonexistent infer = to take a hint, [disputed] to hint inside lane = [U.K.] traffic line next to edge of road, [sometimes in U.S.] traffic lane next to centre of road into = as a divisor of, [in India] multiplied by keep up = to continue to fall (rain), to remain up lash = to secure stably, to fling outwards uncontrolled left = departed from, remaining let = to permit, [archaic] to hinder literally = actually, [disputed] (used before a metaphor) mean = lowly ("rose from mean beginnings"), excellent ("plays a mean trombone") model = archetype, copy moot = debatable, [disputed] not worthy of debate nauseous = nauseating, [disputed] nauseated note = promise to pay, money out = visible (stars), invisible (lights) out of = outside, inside ("work out of one's home") oversight / overlook = care, error peep = to look quietly, to beep peer = noble, person of equal rank priceless = having a value beyond all price, [rare] having no value put out = to generate ("candle puts out light"), to extinguish puzzle = to pose a problem, to solve a problem qualified = competent, limited quantum = very small ("quantum level vs macroscopic level"), [disputed] very large ("quantum leap in productivity") quiddity = essence, trifling point quite = rather, completely ravel = to disentangle, [archaic] to tangle referent = something referred to by something, [disputed] something referring to something rent = to buy temporary use of, to sell temporary use of resign = to quit, [hyphen recommended] to sign up again reword = to repeat in different words, [archaic] to repeat in the same words rummage = [rare] to jumble, [obsolete] to put in order sanction = to approve of, [disputed] to punish [The use of "sanction" as a noun meaning "punishment" is undisputed.] sanguine = hopeful, [obsolete for "sanguinary"] murderous scan = to examine carefully, [disputed] to glance at quickly screen = to show, to hide from view secrete = to extrude, to hide seeded = with seeds, without seeds shank of the evening = end of the evening, early part of the evening skin = to cover with, to remove outer covering straight = not using drugs, [obsolete] under the influence of drugs strand = shore, [Scots] sea substitute = to put (something) in something else's place, [disputed] to replace (something) with something else strike = to miss (baseball), to hit tabby = a silk fabric, a rough kind of concrete table = [U.K.] to propose, [U.S.] to set aside [The UK meaning of "table" is actually more like "to put forward (a document) for consideration" than "to propose" - see the discussion in the newsgroup (start at message no. 13)] temper = calmness, passion think better of = to admire more, to be suspicious of 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"), [U.S. 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") unbending = rigid, relaxing undersexed = having a lower-than-normal sex drive, [disputed] sexually deprived watershed = the divide between regions drained by different rivers, [disputed] the region drained by one river wear = to endure through use, to decay through use weather = to withstand, to wear away widdershins = counterclockwise, [in the southern hemisphere] clockwise wind up = to start ("wind up a watch"), to end with = alongside, against A couple of homophones: aural, oral = heard, spoken erupt, irrupt = burst out, burst in raise, raze = erect, tear down reckless, wreckless = accident prone, no accidents "Used to" is a phrase that can mean "accustomed or habituated to" or refers to something from the past that is no longer true.