The Collaborative International Dictionary of English v.0.48:

Concurrently \Con*cur"rent*ly\, adv.
   With concurrence; unitedly.
   [1913 Webster]

WordNet (r) 3.0 (2006):

concurrently
    adv 1: overlapping in duration; "concurrently with the
           conference an exhibition of things associated with
           Rutherford was held"; "going to school and holding a job
           at the same time" [syn: concurrently, at the same
           time]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "concurrently":
   all agreeing, all together, as one, as one man, at a clip, at once,
   at one time, back to back, by acclamation, cheek by jowl,
   coactively, coefficiently, coincidentally, coinstantaneously,
   collectively, combinedly, communally, concertedly, concordantly,
   conjointly, consentaneously, cooperatingly, cooperatively,
   corporately, hand in glove, hand in hand, harmoniously,
   in a chorus, in agreement, in chorus, in common, in concert with,
   in concord, in harmony with, in partnership, in phase, in sync,
   in unison, inharmony, isochronously, jointly, mutually, nem con,
   nemine contradicente, nemine dissentiente, on all hands,
   on the beat, one and all, shoulder to shoulder, simultaneously,
   synchronously, to a man, together, unanimously, with one accord,
   with one consent, with one voice, without contradiction