prodrome /ˈpɹoʊˌdɹoʊm/noun 3adjective 1forms 1 noun3 •An early sign or symptom (or set of signs and symptoms) warning of the onset of a disease. •(rare) A precursor or harbinger; also a warning event.These may prove the Prodromes […] to the ruin of our Monarchy. — 1643 •An introductory or preliminary book or treatise. adjective1 •(no longer used) Prodromous. formsprodromes