naiad

noun3

1. •
   A female deity (nymph) associated with water, especially a spring, stream, or other fresh water.

   • A Naiad loved him, and forbade him to hold intercourse with any other woman under pain of loss of sight. — 1828
2. •
   The aquatic larva (nymph) of a dragonfly or damselfly.
3. •
   Any of various aquatic plants of the genus Najas.