What is the meaning of Precursor?

That which precurses: a forerunner, predecessor, or indicator of approaching events.

One of the compounds that participates in the chemical reaction that produces another compound.

Caused by the following symbol.

precursory, preceding

precursor

precursor, forerunner

forerunner, precursor

precursor; forerunner (something that led to the development of another)

precursory (pertaining to events that will follow)

precursor

precursory, preceding

precursor, forerunner

Source: wiktionary.org