The Collaborative International Dictionary of English v.0.48:

bop \bop\ n.
   an early form of modern jazz (originating around 1940).

   Syn: bebop.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

BoP
    n 1: the law enforcement agency of the Justice Department that
         operates a nationwide system of prisons and detention
         facilities to incarcerate inmates sentenced to imprisonment
         for federal crimes [syn: Federal Bureau of Prisons,
         BoP]
    2: an early form of modern jazz (originating around 1940) [syn:
       bop, bebop]
    v 1: dance the bebop [syn: bop, bebop]
    2: hit hard [syn: sock, bop, whop, whap, bonk, bash]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "bop":
   acid rock, avant-garde jazz, ballroom music, baloney, bash, bat,
   bebop, belt, biff, bilge, blah, blah-blah, boogie-woogie, bosh,
   bull, bullshit, bunk, bunkum, country rock, crap, dance music,
   dances, douse, flapdoodle, folk rock, gas, guff, gup, hard rock,
   hogwash, hokum, hooey, hot air, hot jazz, jazz, jive,
   mainstream jazz, malarkey, moonshine, musical suite, piffle,
   poppycock, pound, rag, ragtime, rhythm-and-blues, rock,
   rock-and-roll, rot, scat, shit, smack, sock, suite,
   suite of dances, swing, syncopated music, syncopation,
   the new music, tommyrot, tripe, whop, wind