1. Greek mythology: a type of nymph (female spirit) who presided over fountains, wells, springs, streams, brooks and other bodies of fresh water.
2. Biology: the aquatic larva or nymph of a dragonfly, mayfly, or stonefly.
Etymology: Ancient Greek Ναϊάδες, Naiades, from νάειν, “to flow”, or νᾶμα, “running water”.
[Annie Stegg - Lilaia the Naiad]