WordNet (r) 3.0 (2006):

big business
    n 1: commercial enterprises organized and financed on a scale
         large enough to influence social and political policies;
         "big business is growing so powerful it is difficult to
         regulate it effectively"

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "big business":
   balance of trade, business, business dealings, commerce,
   commercial affairs, commercial relations, dealing, dealings,
   fair trade, free trade, industry, intercourse, market, marketing,
   mercantile business, merchantry, multilateral trade,
   reciprocal trade, restraint of trade, small business,
   the business world, the marketplace, trade, traffic, truck,
   unilateral trade