<p><strong>Noun</strong></p><ul><li>(plural: al·ler·gies) an abnormal reaction of the body to a previously encountered allergen introduced by inhalation, ingestion, injection, or skin contact, often manifested by itchy eyes, runny nose, wheezing, skin rash, or diarrhea.</li><li>hypersensitivity to the reintroduction of an allergen.</li><li>Informal: a strong dislike or aversion, as toward a person or activity: He has an allergy to hard work.</li></ul>