The Collaborative International Dictionary of English v.0.48:
Gander \Gan"der\, n. [AS. gandra, ganra, akin to Prov. G. gander, ganter, and E. goose, gannet. See Goose.] The male of any species of goose. [1913 Webster]WordNet (r) 3.0 (2006):
gander n 1: mature male goose