Meaning of precursor

pre•cur•sor

Pronunciation: (pri-kûr'sur, prē'kûr-), [key]
— n.
  1. a person or thing that precedes, as in a job, a method, etc.; predecessor.
  2. a person, animal, or thing that goes before and indicates the approach of someone or something else; harbinger: The first robin is a precursor of spring.
  3. a chemical that is transformed into another compound, as in the course of a chemical reaction, and therefore precedes that compound in the synthetic pathway: Cholesterol is a precursor of testosterone.
  4. a cell or tissue that gives rise to a variant, specialized, or more mature form.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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