'gray comma' definitions:

Definition of 'gray comma'

From: GCIDE

Progne \Prog"ne\ (pr[o^]g"n[-e]), n. [L., a swallow, traditionally said to be fr. Progne (The sister of Philomela), who was changed into a swallow, Gr. Pro`knh.] (Zool.) (a) A swallow. (b) A genus of swallows including the purple martin. See Martin. (c) An American butterfly (Polygonia Progne syn. {Vanessa Progne}). It is orange and black above, grayish beneath, with an L-shaped silver mark on the hind wings. Called also gray comma. [1913 Webster]