What words are their own antonym?

     [This is a fast-access FAQ excerpt.]
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
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 = 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