precursor
Cross references: 1. forerunner pre.cur.sor \pri-'k*r-s*r, 'pre--.\ n [L praecursor, fr. praecursus, pp. of praecurrere to run befo]re, fr. prae- pre- + currere to run - more at CURRENT 1a: one that precedes and indicates the approach of another 1b: PREDECESSOR 2: a substance from which another substance is formed