a cover, or partial cover, for the face, used for disguise or protection; as, a dancer's mask; a fencer's mask; a ball player's mask.-that which disguises; a pretext or subterfuge.-a festive entertainment of dancing or other diversions, where all wear masks; a masquerade; hence, a revel; a frolic; a delusive show.-a dramatic performance, formerly in vogue, in which the actors wore masks and represented mythical or allegorical characters.-a grotesque head or face, used to adorn keystones and other prominent parts, to spout water in fountains, and the like; -- called also mascaron.-in a permanent fortification, a redoubt which protects the caponiere.-a screen for a battery.-the lower lip of the larva of a dragon fly, modified so as to form a prehensile organ.-to cover, as the face, by way of concealment or defense against injury; to conceal with a mask or visor.-to disguise; to cover; to hide.-to conceal; also, to intervene in the line of.-to cover or keep in check; as, to mask a body of troops or a fortess by a superior force, while some hostile evolution is being carried out.-to take part as a masker in a masquerade.-to wear a mask; to be disguised in any way.