Na"iad (?), n. [L. naias, - adis, naïs, -idis, a water nymph, Gr &?;, &?;, fr. &?; to flow: cf. F. naïade. Cf. Naid.] 1. (Myth.) 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.

2. (Zoöl.) Any species of a tribe (Naiades) of freshwater bivalves, including Unio, Anodonta, and numerous allied genera; a river mussel.

3. (Zoöl) One of a group of butterflies. See Nymph.

4. (Bot.) Any plant of the order Naiadaceæ, such as eelgrass, pondweed, etc.

English
• (Greek mythology) a female deity (nymph) associated with water, especially a spring, stream, or other fresh water