The Collaborative International Dictionary of English v.0.48:
Gentlemanlike \Gen"tle*man*like`\, Gentlemanly \Gen"tle*man*ly\, a. Of, pertaining to, resembling, or becoming, a gentleman; befitting a man of good breeding; well-behaved; courteous; polite; as, gentlemanly behavior. [1913 Webster]WordNet (r) 3.0 (2006):
gentlemanlike adj 1: befitting a man of good breeding; "gentlemanly behavior" [syn: gentlemanlike, gentlemanly]