allergen

noun

al·​ler·​gen ˈa-lər-jən 

: a substance (such as pollen) that induces allergy

allergenic

ˌa-lər-ˈje-nik 

adjective

allergenicity

ˌa-lər-jə-ˈni-sə-tē 

noun

Examples of allergen in a Sentence

common allergens, such as pollen

Recent Examples on the Web

This postnatal vitamin includes soy, which is an allergen for some breastfed babies. —Bestreviews, Mercury News, 25 June 2025

So, none of the packaging of the above lists milk among the allergens. —David J. Neal, Miami Herald, 24 June 2025

Then in the brand’s Sesame Miso Salad with Salmon was recalled due to an undeclared allergen. —Moná Thomas, People.com, 23 June 2025

Look for pasta that is free of common allergens, such as milk, soy, fish, shellfish, tree nuts, wheat, eggs and peanuts. —Bestreviews, Chicago Tribune, 18 June 2025

Word History

Etymology

borrowed from German Allergen,, blend of allerg- (in Allergie allergy) and -gen (in Antigen antigen)

Note: See note at allergy.

First Known Use

circa 1907, in the meaning defined above

Kids Definition

allergen

noun

al·​ler·​gen ˈal-ər-jən 

: a substance (as pollen) that causes allergy

allergenic

ˌal-ər-ˈjen-ik 

adjective

Medical Definition

allergen

noun

al·​ler·​gen ˈal-ər-jən 

: a substance that induces allergy

inhaled allergens

a suspected food allergen