a person or thing that precedes, as in a job, a method, etc.; predecessor.
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.
Chemistry, Biochemistry. 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.
Biology. a cell or tissue that gives rise to a variant, specialized, or more mature form.
Origin of precursor
1375–1425; late Middle English <Latin praecursor forerunner. See pre-, cursor
Not only do they come from myriad sources—asphalt is a big one, but paints and other products also release the precursor compounds to pollutants—but the chemical reactions that create these secondary compounds are also complex.
City pavement is a big source of air pollution|Ula Chrobak|September 3, 2020|Popular Science
Continuously monitoring these types of carbon dioxide emissions in the Apennines and other seismically active regions, such as California and Japan, could reveal whether uprising gas is a precursor or product of quakes, he says.
Carbon dioxide from Earth’s mantle may trigger some Italian earthquakes|Maria Temming|August 26, 2020|Science News
SAC is also working on ways to verify the self-reported data behind the scores, as a precursor to making some of the data public next year.
A greener and more compassionate apparel industry|Tate Ryan-Mosley|August 19, 2020|MIT Technology Review
Monkeys’ greater difficulty learning recursive sequences, relative to people, fits a scenario in which “this ability is evolutionarily ancient and could have been a precursor to the development of human grammar,” Ferrigno says.
Monkeys may share a key grammar-related skill with humans|Bruce Bower|June 26, 2020|Science News
Preserving some of the stylized features of its heavy precursor, the lighter Chalcidian helmet was also imbued with practical design upgrades that allowed its wearer to have better hearing and relatively unimpeded vision.
Know Your Ancient Greek Helmets: From Attic to Phrygian|Dattatreya Mandal|May 19, 2020|Realm of History
That convention, though poorly attended, was the precursor to the Constitutional Convention.