The Collaborative International Dictionary of English v.0.48:
hipless \hipless\ adj. having hips which are not prominent; seeming to have no hips; as, slim and hipless; -- of people. Opposite of broad-hipped [WordNet 1.5 +PJC]WordNet (r) 3.0 (2006):
hipless adj 1: having or seeming to have no hips; "slim and hipless" [ant: hipped]