allergen

noun Immunology.

1. any substance, often a protein, that induces an allergy: common allergens include pollen, grasses, dust, and some medications.

noun

1. any substance capable of inducing an allergy

n.

substance causing allergy, 1912, from allergy on model of antigen.

n.

1. A substance, such as pollen, that causes an allergy.
2. antigen

1. A substance, such as pollen, that causes an allergic reaction.