The Collaborative International Dictionary
Antimask
Antimask \An"ti*mask`\ ([a^]n"t[i^]*m[.a]sk`), n.
A secondary mask, or grotesque interlude, between the parts
of a serious mask. [Written also antimasque.]
--Bacon.
Wiktionary
antimask
a. Opposing masks. n. (obsolete form of antimasque English)