pre·cur·sor 
/prɪˈkɚsɚ/ noun
plural pre·cur·sors /prɪˈkɚsɚ/ noun [count] somewhat formal : something that comes before something else and that often leads to or influences its development — often + of or to ▪ Rhythm and blues was a precursor of rock music. ▪ Small tremors may be precursors to big earthquakes.
