synchrony

from WordNet (r) 3.0 (2006)

synchrony
    n 1: the relation that exists when things occur at the same
         time; "the drug produces an increased synchrony of the
         brain waves" [syn: {synchronism}, {synchrony},
         {synchronicity}, {synchroneity}, {synchronization},
         {synchronisation}, {synchronizing}] [ant: {asynchronism},
         {asynchrony}, {desynchronisation}, {desynchronization},
         {desynchronizing}]

from The Collaborative International Dictionary of English v.0.48

Synchrony \Syn"chro*ny\, n.
   The concurrence of events in time; synchronism. [R.]
   [1913 Webster]

         Geological contemporaneity is the same as chronological
         synchrony.                               --Huxley.
   [1913 Webster]