WordNet (r) 3.0 (2006):

cover girl
    n 1: a very pretty girl who works as a photographer's model
         [syn: cover girl, pin-up, lovely]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "cover girl":
   Miss America, bathing beauty, beau ideal, beaut, beauty,
   beauty contest winner, beauty queen, belle, bunny, charmer,
   dazzler, dream, enchantress, great beauty, knockout, lady fair,
   looker, model, paragon, peach, pinup, pinup girl, pussycat,
   raving beauty, reigning beauty, sex kitten, slick chick, stunner