an artificial head of hair, either human or synthetic, worn to disguise baldness, as part of a theatrical or ceremonial dress, as a disguise, or for adornment
1675, shortened form of periwig. Meaning "person who wears a wig (professionally)" is from 1828. The verb meaning "to behave hysterically" (usually with out) is attested from 1955, from notion in to flip one's wig. Cf. dash my wig!, a former mild imprecation (1797), also
wigs on the green (1856), Ir. colloquial for "a fight or rumble" (since wigs are likely to get detached from owners in such an event).