simultaneous

from WordNet (r) 3.0 (2006)

simultaneous
    adj 1: occurring or operating at the same time; "a series of
           coincident events" [syn: {coincident}, {coincidental},
           {coinciding}, {concurrent}, {co-occurrent},
           {cooccurring}, {simultaneous}]

from The Collaborative International Dictionary of English v.0.48

Simultaneous \Si`mul*ta"ne*ous\, a. [LL. simultim at the same
   time, fr. L. simul. See {Simulate}.]
   Existing, happening, or done, at the same time; as,
   simultaneous events. -- {Si`mul*ta"ne*ous*ly}, adv. --
   {Si`mul*ta"ne*ous*ness}, n.
   [1913 Webster]

   {Simultaneous equations} (Alg.), two or more equations in
      which the values of the unknown quantities entering them
      are the same at the same time in both or in all.
      [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

40 Moby Thesaurus words for "simultaneous":
      accessory, accompanying, agreeing, associated, attendant,
      attending, coetaneous, coeternal, coeval, coexistent, coexisting,
      coincident, coinciding, coinstantaneous, collateral, combined,
      concomitant, concurrent, concurring, conjoint, contemporaneous,
      contemporary, conterminous, correlative, coterminous, coupled,
      fellow, isochronal, isochronous, joined, joint, mutual, paired,
      parallel, synchronal, synchronic, synchronous, twin, unison,
      unisonous

[email protected]