what does precursor mean in biology
/preÂ·curÂ·sor/ (preÂ´kur-ser) something that precedes. In biological processes, a substance from which another, usually more active or mature, substance is formed. In clinical medicine, a sign or symptom that heralds another.precurÂ´sory.he storm increase, the flashes succeeded one another more rapidly, the thunder began to growl, and the wind, the precursor of a hurricane, whistled in the plumes and the hair of the horsemen.