Definition of greenfinch:
(n) :
European greenfinch, a common Old World finch (Chloris chloris, syn. Carduelis chloris), mainly green with yellow in the wings and tail.
(n) :
Any bird within the genus Chloris (formerly a subset of the genus Carduelis), small passerine songbirds with yellow-green plumage, found throughout Europe and Asia.
(n) :
(UK military slang, by extension, informal) A female member of the Royal Irish Regiment.
(n) :
(Northern Ireland, historical, informal) A female member of the Ulster Defence Regiment.