Prog"ne (?), n. [L., a swallow, traditionally said to be fr. Progne (The sister of Philomela), who was changed into a swallow, Gr. &?;.] (Zoöl.) (a) A swallow. (b) A genus of swallows including the purple martin. See Martin. (c) An American butterfly (Polygonia, or Vanessa, Progne). It is orange and black above, grayish beneath, with an L-shaped silver mark on the hind wings. Called also gray comma.