'Precursor' definitions:

Definition of 'precursor'

From: WordNet
noun
A substance from which another substance is formed (especially by a metabolic reaction)
noun
A person who goes before or announces the coming of another [syn: precursor, forerunner]
noun
Something that precedes and indicates the approach of something or someone [syn: harbinger, forerunner, predecessor, herald, precursor]

Definition of 'Precursor'

From: GCIDE
  • Precursor \Pre*cur"sor\, n. [L. praecursor, fr. praecurrere to run before; prae before + currere to run. See Course.] One who, or that which, precedes an event, and indicates its approach; a forerunner; a harbinger. [1913 Webster]
  • Evil thoughts are the invisible, airy precursors of all the storms and tempests of the soul. --Buckminster. [1913 Webster]
  • Syn: Predecessor; forerunner; harbinger; messenger; omen; sign. [1913 Webster]

Synonyms of 'precursor'

From: Moby Thesaurus