Definition of "Antecedent" :

noun: the referent of an anaphor; a phrase or clause that is referred to by an anaphoric pronoun

noun: a preceding occurrence or cause or event

noun: someone from whom you are descended (but usually more remote than a grandparent)

noun: anything that precedes something similar in time

"Phrenology was an antecedent of modern neuroscience."

adjective: preceding in time or order