1. 
[syn: big shot, big gun, big wheel, big cheese, big deal, big enchilada, big fish, head honcho]
2.  anything of great importance or consequence; 
WordNet (r) 3.0 (2006):
big deal
    n 1: an important influential person; "he thinks he's a big
         shot"; "she's a big deal in local politics"; "the Qaeda
         commander is a very big fish" [syn: big shot, big gun,
         big wheel, big cheese, big deal, big enchilada,
         big fish, head honcho]
    2: anything of great importance or consequence
Moby Thesaurus II by Grady Ward, 1.0:
23 Moby Thesaurus words for "big deal":
   emptiness, flimsiness, foolishness, frivolity, frivolousness,
   futility, idleness, inanity, levity, lightness, nugacity,
   shallowness, silliness, slenderness, slightness, superficiality,
   triflingness, triteness, triviality, trivialness, vacuity, vanity,
   vapidity