WordNet (r) 3.0 (2006):

masses
    n 1: the common people generally; "separate the warriors from
         the mass"; "power to the people" [syn: multitude,
         masses, mass, hoi polloi, people, the great
         unwashed]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "masses":
   cog, commonality, commonalty, creature, flunky, follower,
   hoi polloi, ignobile vulgus, inferior, junior, lightweight,
   lower class, lower orders, many-headed multitude, mobile vulgus,
   pawn, second fiddle, secondary, subaltern, subordinate,
   the common herd, the crowd, the great unnumbered,
   the great unwashed, the herd, the hoi polloi, the horde,
   the majority, the many, the masses, the mob, the multitude,
   third stringer, underling, understrapper, yes-man