Naiad /(nā"yăd; 277)/

Na·iad

Naiad

n.
  1. A water nymph; one of the lower female divinities, fabled to preside over some body of fresh water, as a lake, river, brook, or fountain. (Myth.)
  2. Any species of a tribe (Naiades) of freshwater bivalves, including Unio, Anodonta, and numerous allied genera; a river mussel. (Zool.)
  3. One of a group of butterflies. See Nymph. (Zool)
  4. Any plant of the order Naiadaceae, such as eelgrass, pondweed, etc. (Bot.)