The Collaborative International Dictionary of English v.0.48:

crowded \crowded\ adj.
   1. overfilled or compacted or concentrated; filled to excess;
      as, a crowded program. Opposite of uncrowded.

   Note: [Narrower terms: full, jammed, jam-packed, packed]
         [WordNet 1.5]

   2. filled with a crowd; as, a crowded marketplace.
      [PJC]

   3. having an uncomfortable density of people; filled to
      excess with people; as, crowded trains; a crowded theater.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Crowd \Crowd\ (kroud), v. t. [imp. & p. p. Crowded; p. pr. &
   vb. n. Crowding.] [OE. crouden, cruden, AS. cr[=u]dan; cf.
   D. kruijen to push in a wheelbarrow.]
   1. To push, to press, to shove. --Chaucer.
      [1913 Webster]

   2. To press or drive together; to mass together. "Crowd us
      and crush us." --Shak.
      [1913 Webster]

   3. To fill by pressing or thronging together; hence, to
      encumber by excess of numbers or quantity.
      [1913 Webster]

            The balconies and verandas were crowded with
            spectators, anxious to behold their future
            sovereign.                            --Prescott.
      [1913 Webster]

   4. To press by solicitation; to urge; to dun; hence, to treat
      discourteously or unreasonably. [Colloq.]
      [1913 Webster]

   To crowd out, to press out; specifically, to prevent the
      publication of; as, the press of other matter crowded out
      the article.

   To crowd sail (Naut.), to carry an extraordinary amount of
      sail, with a view to accelerate the speed of a vessel; to
      carry a press of sail.
      [1913 Webster]

WordNet (r) 3.0 (2006):

crowded
    adj 1: overfilled or compacted or concentrated; "a crowded
           theater"; "a crowded program"; "crowded trains"; "a young
           mother's crowded days" [ant: uncrowded]