The Collaborative International Dictionary of English v.0.48:

bullshit \bullshit\ n.
   a ludicrously false statement. [vulgar]

   Syn: bull, Irish bull, horseshit, shit, crap, crapola, bunk,
        bunkum, buncombe, guff, rot, tommyrot, balderdash,
        hogwash, dogshit.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

bullshit \bullshit\ v.
   to talk through one's hat. [vulgar]

   Syn: waffle, bull, fake.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

bullshit
    n 1: obscene words for unacceptable behavior; "I put up with a
         lot of bullshit from that jerk"; "what he said was mostly
         bull" [syn: bullshit, bull, Irish bull, horseshit,
         shit, crap, dogshit]
    v 1: speak insincerely or without regard for facts or truths;
         "The politician was not well prepared for the debate and
         faked it" [syn: talk through one's hat, bullshit,
         bull, fake]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "bullshit":
   babble, balderdash, balls, baloney, big talk, bilge, blabber,
   blague, blah, blah-blah, blather, bop, bosh, bull, bunk, bunkum,
   claptrap, crap, drivel, drool, eyewash, fancy talk, fine talk,
   fish story, flam, flapdoodle, flimflam, gabble, gammon, gas,
   gibber, gibble-gabble, guff, gup, highfalutin, highfaluting,
   hogwash, hoke, hokum, hooey, hot air, humbug, humbuggery, jabber,
   jiggery-pokery, malarkey, moonshine, piffle, poppycock, prate,
   prattle, rattle, rot, scat, shit, talk nonsense, tall story,
   tall talk, tommyrot, tripe, twaddle, twattle, vapor, waffle,
   wind