precursor Meaning, Definition & Usage

  1. noun a substance from which another substance is formed (especially by a metabolic reaction)
  2. noun a person who goes before or announces the coming of another
    forerunner.
  3. noun something that precedes and indicates the approach of something or someone
    predecessor; herald; forerunner; harbinger.

WordNet

Pre*cur"sor noun
Etymology
L. praecursor, fr. praecurrere to run before; prae before + currere to run. See Course.
Definitions
  1. One who, or that which, precedes an event, and indicates its approach; a forerunner; a harbinger.
    Evil thoughts are the invisible, airy precursors of all the storms and tempests of the soul. Buckminster.
    Syn. -- Predecessor; forerunner; harbinger; messenger; omen; sign.

Webster 1913