Definition of antedated:
(v) :
To occur before an event or time; to exist further back in time.
(v) :
To assign a date to a document or action earlier than the actual date.
(n) :
Prior date; a date antecedent to another which is the actual date.
(v) :
(lexicography) To find earlier citational evidence for a term.
(n) :
(obsolete) anticipation