mid-14c., mermayde, literally "maid of the sea," from Middle English mere "sea, lake" (see mere (n.)) + maid. Old English had equivalent merewif "water-witch" (see wife), meremenn "mermaid, siren." Tail-less in northern Europe; the fishy form is a medieval influence from classical sirens. A favorite sign of taverns and inns at least since early 15c. (in reference to the inn on Bread Street, Cheapside, London). Mermaid pie (1660s) was "a sucking pig baked whole in a crust."