Mer″maid (?), n. [AS. mere lake, sea. See Mere lake, and maid.] A fabled marine creature, typically represented as having the upper part like that of a woman, and the lower like a fish; a sea nymph, sea woman, or woman fish.
☞ Chaucer uses this word as equivalent to the siren of the ancients.
Mermaid fish(Zoöl.) the angel fish (Squatina). — Mermaid's glove(Zoöl.), a British branched sponge somewhat resembling a glove. — Mermaid's head(Zoöl.), a European spatangoid sea urchin (Echinocardium cordatum) having some resemblance to a skull. — Mermaid weed(Bot.), an aquatic herb with dentate or pectinate leaves (Proserpinaca palustris and P. pectinacea).