Source : Webster's Revised Unabridged Dictionary (1913)

Concomitance \Con*com"i*tance\, Concomitancy \Con*com"i*tan*cy\,
   n. [Cf. F. concomitance, fr. LL. concomitantia.]
   1. The state of accompanying; accompaniment.

            The secondary action subsisteth not alone, but in
            concomitancy with the other.          --Sir T.
                                                  Browne.

   2. (R.C.Ch.) The doctrine of the existence of the entire body
      of Christ in the eucharist, under each element, so that
      the body and blood are both received by communicating in
      one kind only.

Source : WordNet®

concomitance
     n : occurrence or existence together or in connection with one
         another