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

When exposed, the body produces an antibody known as Immunoglobulin E (IgE), which binds to the allergen and triggers immune cells to release histamine and other chemicals. —New Atlas, 3 July 2025

Prime subscribers can also score savings on household essentials, like a best-selling Levoit air purifier, which tackles airborne allergens and pollutants, plus a cordless vacuum that doubles as a handheld to clean above-ground messes. —Clara McMahon, People.com, 2 July 2025

Rugs, upholstered furniture, and antiques should be thoroughly cleaned or professionally treated to remove dirt, allergens, and any unwelcome critters. —Brandee Gruener, Southern Living, 29 June 2025

This helps capture fine particles and allergens—sometimes up to 99.99%—for an incredibly thorough clean. —Nashia Baker, Architectural Digest, 26 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