Real Dictionary

encore
countable noun: An encore is a short extra performance at the end of a longer one, which an entertainer gives because the audience asks for it.
verb: If an entertainer encores, they perform an encore.

encore in American English
again; once more
interjection: again; once more (used by an audience in calling for an additional number or piece)
noun: a demand, as by applause, for a repetition of a song, act, etc., or for a performance of a number or piece additional to those on a program, or for a reappearance by the performers, as at the end of a concert, recital, etc
transitive verb: to call for a repetition of

encore in British English
exclamation: again; once more: used by an audience to demand an extra or repeated performance
noun: an extra or repeated performance given in response to enthusiastic demand
verb: to demand an extra or repeated performance of (a work, piece of music, etc) by (a performer)