Source : Webster's Revised Unabridged Dictionary (1913)

Encore \En`core"\, adv. or interj. [F. The last part of the word
   is fr. L. hora hour. See {Hour}.]
   Once more; again; -- used by the auditors and spectators of
   plays, concerts, and other entertainments, to call for a
   repetition of a particular part.

Encore \En`core"\, n.
   A call or demand (as, by continued applause) for a
   repetition; as, the encores were numerous.

Encore \En`core"\, v. t. [imp. & p. p. {Encored}; p. pr. & vb.
   n. {Encoring}.]
   To call for a repetition or reappearance of; as, to encore a
   song or a singer.

         [Rebecca] insisted upon encoring one of the duets.
                                                  --Thackeray.

Source : WordNet®

encore
     n : an extra or repeated performance; usually given in response
         to audience demand
     v : request an encore, from a performer