1. adjective
a) Being of the genus Cygnus (swan), within subfamily Anserinae of the family Anatidae, though sometimes considered a distinct subfamily, Cygninae.
The genus Choristopus, Eyton, apparently Anserine rather than Cygnine, is said to possess this character
b) Of, concerning, pertaining to, resembling, or having the characteristics of a swan or swans.
But, in the cutting of it, if thou dost shed / One drop of cygnine blood, thy clumsiness...
2. noun
An alkaloid from , the York Road poison plant; a convulsant poison, CHNO.
Wikipedia foundation.