The Collaborative International Dictionary of English v.0.48:

Snobbish \Snob"bish\, a.
   Of or pertaining to a snob; characteristic of, or befitting,
   a snob; vulgarly pretentious. -- Snob"bish*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

snobbish
    adj 1: befitting or characteristic of those who incline to
           social exclusiveness and who rebuff the advances of
           people considered inferior [syn: clannish, cliquish,
           clubby, snobbish, snobby]

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "snobbish":
   affected, aloof, arrogant, clannish, cliquish, complacent,
   conceited, condescending, contemptuous, contumelious, disdainful,
   egotistical, elect, ethnocentric, exceptional, excluding,
   exclusive, exclusory, haughty, high and mighty, high-flown,
   high-hat, highfalutin, hoity-toity, inadmissible, insecure,
   insular, lofty, lordly, narrow, parochial, patronizing, pompous,
   potty, preclusive, prescriptive, pretentious, preventive, priggish,
   prohibitive, putting on airs, remote, restrictive, ritzy, scornful,
   seclusive, segregative, select, selective, self-important,
   self-satisfied, separative, smug, sneering, sniffy, snippy, snobby,
   snooty, snotty, stuck-up, supercilious, superior, toploftical,
   toplofty, uncertain, unconfident, unsure, uppish, uppity, vain,
   withering, xenophobic