mum·mer
Pronunciation: \ˈmə-mər\
Function: noun
Date: 1502
1 : a performer in a pantomime; broadly : ACTOR
2 : one who goes merrymaking in disguise during festivals
We promise that it ain't pantomime...
Wikipedia
Strictly speaking, a mummer is an actor in a traditional seasonal folk play. The term is also humorously (or derogatorily) applied to any actor.
