The Collaborative International Dictionary of English v.0.48:
Yesteryear \Yes"ter*year`\, n. The year last past; last year. [1913 Webster]WordNet (r) 3.0 (2006):
yesteryear n 1: the time that has elapsed; "forget the past" [syn: past, past times, yesteryear] [ant: future, futurity, hereafter, time to come]