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.
   [1913 Webster]

         Are come to play a pleasant comedy.      --Shak.
   [1913 Webster]

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.
      [1913 Webster]

   2. A series of real events invested with a dramatic unity and
      interest. "The drama of war." --Thackeray.
      [1913 Webster]

            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.
      [1913 Webster]

            The drama and contrivances of God's providence.
                                                  --Sharp.
      [1913 Webster]

   3. Dramatic composition and the literature pertaining to or
      illustrating it; dramatic literature.
      [1913 Webster]

   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]

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "comedy":
   Atticism, Thalia, agile wit, arlequinade, black comedy,
   black humor, bladder, broad comedy, burlesque, burletta, camp,
   cap and bells, caricature, comedie bouffe, comedie larmoyante,
   comedie rosse, comedietta, comedy ballet, comedy of humors,
   comedy of ideas, comedy of intrigue, comedy of manners,
   comedy of situation, comedy relief, comic muse, comic opera,
   comic relief, comicality, comicalness, coxcomb, dark comedy,
   domestic comedy, drollery, drollness, dry wit, esprit, exode,
   farce, farce comedy, funniness, genteel comedy, harlequinade,
   high camp, humor, humorousness, irony, lampoon, light comedy,
   low camp, low comedy, mime, motley, musical, musical comedy,
   nimble wit, opera buffa, parody, pleasantry, pretty wit, quick wit,
   raw comedy, ready wit, realistic comedy, romantic comedy, salt,
   sarcasm, satire, satyr play, savor of wit, sentimental comedy,
   situation comedy, slapstick, slapstick comedy, slapstick humor,
   sock, squib, subtle wit, tragicomedy, travesty, visual humor, wit,
   wittiness