\Ne"re*id\, n.; pl. E. {Nereids}, L. {Nereides}. [L.
Nereis, -idis, gr. Nhrei:`s Nhrhi:`s, i:`dos, a daughter of
Nereus, a nymph of the sea, fr. Nhrey`s Nereus, an ancient
sea god; akin to nhro`s wet, Skr. n[=a]ra water, cf. Gr.
na`ein to flow.]
1. (Class. Myth.) A sea nymph, one of the daughters of
   Nereus, who were attendants upon Neptune, and were
   represented as riding on sea horses, sometimes with the
   human form entire, and sometimes with the tail of a fish.

2. (Zo["o]l.) Any species of Nereis. The word is sometimes
   used for similar annelids of other families.