Definition of "allergen" []

• A substance, such as pollen, that causes an allergy. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Cover pillows, mattress, and box spring in allergen-proof casings."
• "Cover pillow, mattress, and box spring in allergen-proof casings."
• "Researchers at Germany's University of Hohenheim have reported that fermentation of skim milk and sweet whey with a one-to-one mixture of the bacteria could reduce the quantity of beta-lactoglobulin, the main allergen in cows milk, by as much as 90 per cent."