allergen
noun
- type of antigen that produces an abnormally vigorous immune response, in which the immune system reacts to fight off a perceived threat that would otherwise be harmless to the body
- protein
Wiktionary
Pronunciation: /ˈælə(ɹ)ˌd͡ʒɛn/
noun
Etymology: Syncopated compound of allergy + -gen, coined on the model of pharmaceutical words such as pathogen and antigen.
- A substance which causes an allergic reaction.
“Pollen, dust, and spores are common allergens.”