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]