hipless

from WordNet (r) 3.0 (2006)

hipless
    adj 1: having or seeming to have no hips; "slim and hipless"
           [ant: {hipped}]

from 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]