The Collaborative International Dictionary of English v.0.48:

Comedy \Com"e*dy\, n.; pl. Comedies. [F. com['e]die, L.
   comoedia, fr. Gr. ?; ? a jovial festivity with music and
   dancing, a festal procession, an ode sung at this procession
   (perh. akin to ? village, E. home) + ? to sing; for comedy
   was originally of a lyric character. See Home, and Ode.]
   A dramatic composition, or representation of a bright and
   amusing character, based upon the foibles of individuals, the
   manners of society, or the ludicrous events or accidents of
   life; a play in which mirth predominates and the termination
   of the plot is happy; -- opposed to tragedy.
   [1913 Webster]

         With all the vivacity of comedy.         --Macaulay.
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         Are come to play a pleasant comedy.      --Shak.
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The Collaborative International Dictionary of English v.0.48:

Drama \Dra"ma\ (dr[aum]"m[.a] or dr[=a]"m[.a]; 277), n. [L.
   drama, Gr. dra^ma, fr. dra^n to do, act; cf. Lith. daryti.]
   1. A composition, in prose or poetry, accommodated to action,
      and intended to exhibit a picture of human life, or to
      depict a series of grave or humorous actions of more than
      ordinary interest, tending toward some striking result. It
      is commonly designed to be spoken and represented by
      actors on the stage.
      [1913 Webster]

            A divine pastoral drama in the Song of Solomon.
                                                  --Milton.
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   2. A series of real events invested with a dramatic unity and
      interest. "The drama of war." --Thackeray.
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            Westward the course of empire takes its way;
            The four first acts already past,
            A fifth shall close the drama with the day;
            Time's noblest offspring is the last. --Berkeley.
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            The drama and contrivances of God's providence.
                                                  --Sharp.
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   3. Dramatic composition and the literature pertaining to or
      illustrating it; dramatic literature.
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   Note: The principal species of the drama are tragedy and
         comedy; inferior species are tragi-comedy,
         melodrama, operas, burlettas, and farces.
         [1913 Webster]

   The romantic drama, the kind of drama whose aim is to
      present a tale or history in scenes, and whose plays (like
      those of Shakespeare, Marlowe, and others) are stories
      told in dialogue by actors on the stage. --J. A. Symonds.
      Dramatic

WordNet (r) 3.0 (2006):

comedy
    n 1: light and humorous drama with a happy ending [ant:
         tragedy]
    2: a comic incident or series of incidents [syn: drollery,
       clowning, comedy, funniness]