Our online medical glossary of medical terms and definitions includes definitions for terms related to treatment, and general medicine
1. The name of different species of herons which bear plumes on the back. They are usually white. Among the excellent known species are the American egret (Ardea, or Herodias, egretta); the great egret (A. Alba); the few egret (A. Garzetta), of Europe; and the American snowyegret (A. Candidissima). "A bunch of egrets killed for their plumage." (G. W. Cable)
2. A plume or tuft of feathers worn as a part of a headdress, or anything imitating such an ornament; an aigrette.
3. The flying feathery or hairycrown of seeds or achenes, as the down of the thistle.
4. A kind of ape.
See: Aigret, Heron.
Source: Websters Vocabulary