The Collaborative International Dictionary of English v.0.48:

Unanimous \U*nan"i*mous\ ([-u]*n[a^]n"[i^]*m[u^]s), a. [L.
   unanimus, unanimis; unus one + animus mind: cf. F. unanime.
   See Unit, and Animate.]
   1. Being of one mind; agreeing in opinion, design, or
      determination; consentient; not discordant or dissentient;
      harmonious; as, the assembly was unanimous; the members of
      the council were unanimous. "Both in one faith unanimous."
      --Milton.
      [1913 Webster]

   2. Formed with unanimity; indicating unanimity; having the
      agreement and consent of all; agreed upon without the
      opposition or contradiction of any; as, a unanimous
      opinion; a unanimous vote.
      [1913 Webster] -- U*nan"i*mous*ly, adv. --
      U*nan"i*mous*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unanimously
    adv 1: of one mind; without dissent; "the Senate unanimously
           approved the bill"; "we voted unanimously" [syn:
           unanimously, nem con, nemine contradicente]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "unanimously":
   agreeably, all agreeing, all together, as one, as one man,
   back to back, by acclamation, by consensus, coactively,
   coefficiently, collectively, combinedly, communally, compatibly,
   concertedly, concordantly, concurrently, congenially, conjointly,
   consentaneously, consonantly, cooperatingly, cooperatively,
   fittingly, hand in glove, hand in hand, harmoniously, in chorus,
   in concert, in concert with, in keeping, in line, in step,
   in unison, jointly, just right, nem con, nemine contradicente,
   nemine dissentiente, on all hands, one and all,
   shoulder to shoulder, to a man, together, with it, with one accord,
   with one consent, with one voice, without contradiction