WordNet (r) 3.0 (2006):

Priapus
    n 1: (classical mythology) god of male procreative power and
         guardian of gardens and vineyards

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "Priapus":
   Ashtoreth, Astarte, Baal, Cailleac, Ceres, Demeter, Dionysus,
   Faunus, Frey, Isis, Pan, Vidar, Vitharr, aphrodisiomaniac,
   corn spirit, dirty old man, eroticomaniac, erotomaniac, faun,
   fertility god, field spirit, forest god, goat, gynecomaniac,
   lecher, old goat, panisc, panisca, paniscus, satyr, silenus,
   sylvan deity, the goat god, vegetation spirit, whoremaster,
   whoremonger