WordNet (r) 3.0 (2006):

pin-up
    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:

61 Moby Thesaurus words for "pinup":
   Miss America, Telephoto, Wirephoto, aerial photograph,
   bathing beauty, beau ideal, beaut, beauty, beauty contest winner,
   beauty queen, belle, black-and-white photograph, bunny,
   candid photograph, charmer, cheesecake, chronophotograph,
   color photograph, color print, cover girl, dazzler, diapositive,
   dream, enchantress, great beauty, heliochrome, heliograph,
   knockout, lady fair, looker, model, montage, mug, mug shot,
   paragon, peach, photo, photobiography, photochronograph,
   photograph, photomap, photomicrograph, photomontage, photomural,
   picture, pinup girl, portrait, pussycat, raving beauty,
   reigning beauty, sex kitten, shot, slick chick, slide, snap,
   snapshot, still, still photograph, stunner, telephotograph,
   transparency