Definition of "simultaneous"

simultaneous

/ˌsɪm.əlˈteɪ̯.ni.əs/

adjective
not comparable
1. Happening at the same moment.
  Quotations
  As with the Lejeuneaceae, this pattern of massive speciation appears to be correlated with the Cretaceous explosion of the angiosperms and the simultaneous creation of a host of new microenvironments, differing in humidity, light intensity, texture, etc.
  1992, Rudolf M[athias] Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, New York, N.Y.: Columbia University Press, pages 3-4
2. (mathematics, of a set of equations) To be solved for the same values of variables.