precursor (n.)

early 15c., precursoure, "a forerunner; that which precedes an event and indicates its approach," from Old French precurseur and directly from Latin praecursor "forerunner," agent noun from past-participle stem of praecurrere, from prae "before" (see pre-) + currere "to run" (from PIE root *kers- "to run"). Originally of John the Baptist. Related: Precursive; precursory.