WordNet (r) 3.0 (2006):

heartthrob
    n 1: an object of infatuation

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "heartthrob":
   affect, affection, arrhythmia, beat, beating, beloved, darling,
   drumming, emotion, emotional charge, emotional shade, experience,
   feeling, feeling tone, flame, flutter, foreboding, gut reaction,
   heartbeat, honey, impression, love, palpitation, passion, pitapat,
   pitter-patter, presentiment, profound sense, pulsation, pulse,
   rat-a-tat, rataplan, reaction, response, rhythm, sensation, sense,
   sentiment, staccato, throb, throbbing, turtledove, undercurrent