Allergen (noun)

Any substance that can cause an allergic reaction in some people.

Origin:

Allergen is a combination of "allergy" and "gen" which means producing, the word was coined in the late 19th century, and it refers to any substance that can cause an allergic reaction in some people.

Examples:

1. Common allergens include pollen, pet dander, and dust mites.
2. The allergen was identified as peanuts.
3. Some people have an allergic reaction to certain foods, such as nuts and shellfish.
4. The allergen was found to be present in the air conditioning system.
5. The allergen was identified as a chemical used in the manufacturing process.