WordWeb Online

1. (often followed by 'of') a large number, amount or extent
   "a great deal of letters";
   - batch, deal, flock, good deal, hatful, heap, lot, mass, mess, mickle [archaic], mint, mountain, muckle, passel [US], peck, pile [informal], plenty, pot, quite a little, raft, sight, slew, spate, stack, tidy sum, wad, bunch [informal]

Derived forms: great deals

Type of: large indefinite amount, large indefinite quantity