Mermaid

n.
  1. 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.
    2. 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 Proserpinaca pectinacea).