From WordNet (r) 3.0 (2006):
past
adv 1: so as to pass a given point; "every hour a train goes
past" [syn: by, past]
adj 1: earlier than the present time; no longer current; "time
past"; "his youth is past"; "this past Thursday"; "the
past year" [ant: future, present(a)]
2: of a person who has held and relinquished a position or
office; "a retiring member of the board" [syn: past(a),
preceding(a), retiring(a)]
n 1: the time that has elapsed; "forget the past" [syn: past,
past times, yesteryear] [ant: future, futurity,
hereafter, time to come]
2: a earlier period in someone's life (especially one that they
have reason to keep secret); "reporters dug into the
candidate's past"
3: a verb tense that expresses actions or states in the past
[syn: past, past tense]