The Collaborative International Dictionary of English v.0.48:

pants \pants\ n.
   1. n. pl. A garment extending from the waist to the knee or
      ankle, covering each leg separately.

   Syn: trousers.
        [WordNet 1.6]

   2. Underpants.

   Syn: drawers.
        [PJC]

   3. Specifically: Underpants worn by women; panties.

   Syn: bloomers, drawers, panties.
        [WordNet 1.6]

WordNet (r) 3.0 (2006):

pants
    n 1: underpants worn by women; "she was afraid that her bloomers
         might have been showing" [syn: bloomers, pants,
         drawers, knickers]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "pants":
   Bermuda shorts, Capri pants, bags, bells, bloomers, blue jeans,
   breeches, breeks, briefs, britches, buckskins, chivarras,
   clam diggers, cords, corduroys, culottes, denims, drawers,
   dungarees, flannels, hot pants, jeans, jodhpurs, knee breeches,
   knickerbockers, knickers, overalls, pair of trousers, pajamas,
   pantalets, pantaloons, panties, peg pants, pegtops, plus-fours,
   rompers, sacks, shintiyan, shorts, slacks, smallclothes, tights,
   trews, trousers, trunks, tweeds, underpants, undies, whites