The Collaborative International Dictionary of English v.0.48:

Forget \For*get"\, v. t. [imp. Forgot(Forgat, Obs.); p. p.
   Forgotten, Forgot; p. pr. & vb. n. Forgetting.] [OE.
   forgeten, foryeten, AS. forgietan, forgitan; pref. for- +
   gietan, gitan (only in comp.), to get; cf. D. vergeten, G.
   vergessen, Sw. f["o]rg[aum]ta, Dan. forgiette. See For-,
   and Get, v. t.]
   1. To lose the remembrance of; to let go from the memory; to
      cease to have in mind; not to think of; also, to lose the
      power of; to cease from doing.
      [1913 Webster]

            Bless the Lord, O my soul, and forget not all his
            benefits.                             --Ps. ciii. 2.
      [1913 Webster]

            Let my right hand forget her cunning. --Ps. cxxxvii.
                                                  5.
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            Hath thy knee forget to bow?          --Shak.
      [1913 Webster]

   2. To treat with inattention or disregard; to slight; to
      neglect.
      [1913 Webster]

            Can a woman forget her sucking child? . . . Yes,
            they may forget, yet will I not forget thee. --Is.
                                                  xlix. 15.
      [1913 Webster]

   To forget one's self.
      (a) To become unmindful of one's own personality; to be
          lost in thought.
      (b) To be entirely unselfish.
      (c) To be guilty of what is unworthy of one; to lose one's
          dignity, temper, or self-control.
          [1913 Webster]

WordNet (r) 3.0 (2006):

forget
    v 1: dismiss from the mind; stop remembering; "I tried to bury
         these unpleasant memories" [syn: forget, bury] [ant:
         remember, think of]
    2: be unable to remember; "I'm drawing a blank"; "You are
       blocking the name of your first wife!" [syn: forget,
       block, blank out, draw a blank] [ant: call back,
       call up, recall, recollect, remember, retrieve,
       think]
    3: forget to do something; "Don't forget to call the chairman of
       the board to the meeting!" [ant: bear in mind, mind]
    4: leave behind unintentionally; "I forgot my umbrella in the
       restaurant"; "I left my keys inside the car and locked the
       doors" [syn: forget, leave]