The Collaborative International Dictionary of English v.0.48:
Eyesore \Eye"sore`\, n. Something offensive to the eye or sight; a blemish. [1913 Webster] Mordecai was an eyesore to Haman. --L'Estrange. [1913 Webster]WordNet (r) 3.0 (2006):
eyesore n 1: something very ugly and offensive