eus·the·nop·te·ron \ˌyüsthəˈnäptəˌrän\noun Usage: capitalized Etymology: New Latin, from eustheno- (from Greek eusthenēs strong, from eu- + -sthenēs, from sthenos strength) + Greek pteron wing; from the strongly developed fins — more at asthen-, feather : a genus of Upper Devonian lobe-finned fishes (order Rhipidistia)