Allergen

Part of speech: noun

Pronunciation: /ˈælə(ɹ)ˌd͡ʒɛn/

Definitions

1. A substance that triggers an immune system reaction in susceptible individuals, causing symptoms such as itching, swelling, or respiratory difficulty
2. A substance that provokes an adverse immune response in sensitive individuals, resulting in reactions like hives, inflammation, or breathing challenges
3. A material that incites a negative response from the immune system in predisposed people, often leading to symptoms such as rashes, swelling, or respiratory issues

Etymology: "Allergen" is a modern coinage built from Greek parts: "allos" meaning "other" and "ergon" meaning "work" or "action," combined so that the first part gives us "allergy," a reaction in which the body responds abnormally to a substance. The word for the substance itself came from the same stem, with "-gen" added from Greek "-genes," meaning "producing" or "born of," the same ending seen in "pathogen" and "antigen." The "-gen" element works as a suffix that marks something causing a condition. A pathogen causes disease and an antigen provokes an immune response, and "allergen" follows that pattern: it is the thing that produces the allergic reaction. The construction is deliberately modern, and it reflects the scientific vocabulary of the late nineteenth and early twentieth centuries, when physicians and researchers were naming newly understood processes.

Synonyms: antigen, substance, irritant

Antonyms: tolerance, immunity