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

Today's shoppers are more health-conscious than ever, and manufacturers are aware that many people have specific food allergens or eating plans. —Matt Emma, USA Today, 8 Dec. 2025

The sandwiches may be incorrectly labeled as the cheese variety, resulting in an undeclared peanut allergen. —Jenna Anderson, Health, 3 Dec. 2025

Best Amazon Cyber Monday Upright Vacuum Deals Amazon is also serving up discounts on upright vacuum cleaners, like the best-selling Shark Lift-Away vacuum, which packs serious suction power and traps allergens with ease. —Toni Sutton, PEOPLE, 1 Dec. 2025

Numerous food recalls were initiated nationwide this month due to undeclared allergens, potential Salmonella and Listeria contamination concerns, and possible cleaning agent contamination, among other reasons. —Anna Skinner, MSNBC Newsweek, 30 Nov. 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