The Collaborative International Dictionary of English v.0.48:

Collectively \Col*lect"ive*ly\, adv.
   In a mass, or body; in a collected state; in the aggregate;
   unitedly.
   [1913 Webster]

WordNet (r) 3.0 (2006):

collectively
    adv 1: in conjunction with; combined; "our salaries put together
           couldn't pay for the damage"; "we couldn't pay for the
           damages with all our salaries put together" [syn:
           jointly, collectively, conjointly, together with]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "collectively":
   across the board, all, all at once, all put together, altogether,
   as a body, as a whole, as one, as one man, at large, back to back,
   bodily, coactively, coefficiently, combinedly, communally,
   concertedly, concordantly, concurrently, conjointly, cooperatingly,
   cooperatively, corporately, en bloc, en masse, ensemble, entirely,
   hand in glove, hand in hand, harmoniously, in a body, in all,
   in all respects, in association, in bulk, in chorus, in company,
   in concert with, in conjunction, in its entirety, in the aggregate,
   in the gross, in the lump, in the mass, in toto, in unison,
   jointly, mutually, on all counts, shoulder to shoulder, together,
   totally, tout ensemble, unanimously, unitedly, wholly,
   with one voice