The Collaborative International Dictionary of English v.0.48:

Eat \Eat\ ([=e]t), v. t. [imp. Ate ([=a]t; 277), Obsolescent &
   Colloq. Eat ([e^]t); p. p. Eaten ([=e]t"'n), Obs. or
   Colloq. Eat ([e^]t); p. pr. & vb. n. Eating.] [OE. eten,
   AS. etan; akin to OS. etan, OFries. eta, D. eten, OHG. ezzan,
   G. essen, Icel. eta, Sw. [aum]ta, Dan. [ae]de, Goth. itan,
   Ir. & Gael. ith, W. ysu, L. edere, Gr. 'e`dein, Skr. ad.
   [root]6. Cf. Etch, Fret to rub, Edible.]
   1. To chew and swallow as food; to devour; -- said especially
      of food not liquid; as, to eat bread. "To eat grass as
      oxen." --Dan. iv. 25.
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            They . . . ate the sacrifices of the dead. --Ps.
                                                  cvi. 28.
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            The lean . . . did eat up the first seven fat kine.
                                                  --Gen. xli.
                                                  20.
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            The lion had not eaten the carcass.   --1 Kings
                                                  xiii. 28.
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            With stories told of many a feat,
            How fairy Mab the junkets eat.        --Milton.
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            The island princes overbold
            Have eat our substance.               --Tennyson.
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            His wretched estate is eaten up with mortgages.
                                                  --Thackeray.
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   2. To corrode, as metal, by rust; to consume the flesh, as a
      cancer; to waste or wear away; to destroy gradually; to
      cause to disappear.
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   To eat humble pie. See under Humble.

   To eat of (partitive use). "Eat of the bread that can not
      waste." --Keble.

   To eat one's words, to retract what one has said. (See the
      Citation under Blurt.)

   To eat out, to consume completely. "Eat out the heart and
      comfort of it." --Tillotson.

   To eat the wind out of a vessel (Naut.), to gain slowly to
      windward of her.

   Syn: To consume; devour; gnaw; corrode.
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The Collaborative International Dictionary of English v.0.48:

Eat \Eat\, v. i.
   1. To take food; to feed; especially, to take solid, in
      distinction from liquid, food; to board.
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            He did eat continually at the king's table. --2 Sam.
                                                  ix. 13.
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   2. To taste or relish; as, it eats like tender beef.
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   3. To make one's way slowly.
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   To eat, To eat in or To eat into, to make way by
      corrosion; to gnaw; to consume. "A sword laid by, which
      eats into itself." --Byron.

   To eat to windward (Naut.), to keep the course when
      closehauled with but little steering; -- said of a vessel.
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WordNet (r) 3.0 (2006):

eat
    v 1: take in solid food; "She was eating a banana"; "What did
         you eat for dinner last night?"
    2: eat a meal; take a meal; "We did not eat until 10 P.M.
       because there were so many phone calls"; "I didn't eat yet,
       so I gladly accept your invitation"
    3: take in food; used of animals only; "This dog doesn't eat
       certain kinds of meat"; "What do whales eat?" [syn: feed,
       eat]
    4: worry or cause anxiety in a persistent way; "What's eating
       you?" [syn: eat, eat on]
    5: use up (resources or materials); "this car consumes a lot of
       gas"; "We exhausted our savings"; "They run through 20
       bottles of wine a week" [syn: consume, eat up, use up,
       eat, deplete, exhaust, run through, wipe out]
    6: cause to deteriorate due to the action of water, air, or an
       acid; "The acid corroded the metal"; "The steady dripping of
       water rusted the metal stopper in the sink" [syn: corrode,
       eat, rust]

The Devil's Dictionary (1881-1906):

EAT, v.i.  To perform successively (and successfully) the functions of
mastication, humectation, and deglutition.
    "I was in the drawing-room, enjoying my dinner," said Brillat-
Savarin, beginning an anecdote.  "What!" interrupted Rochebriant;
"eating dinner in a drawing-room?"  "I must beg you to observe,
monsieur," explained the great gastronome, "that I did not say I was
eating my dinner, but enjoying it.  I had dined an hour before."