What do a.m. and p.m. stand for?


[al-er-juh n, -jen] /ˈæl ər dʒən, -ˌdʒɛn/
noun, Immunology
any substance, often a protein, that induces an allergy: common allergens include pollen, grasses, dust, and some medications.
Origin of allergen
1910-15; aller(gy) + -gen Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
Cite This Source
Examples from the web for allergen
  • While some individuals build up immunities from multiple exposures to an allergen, others will develop sensitivities.
  • It's a deadly allergen to some people, but irresistible to rodents.
  • It turns out that a fragrance used in many shampoos is a common allergen that may even cause eczema.
  • The researchers found there were no differences in allergen levels between hypoallergenic dogs and non-hypoallergenic ones.
  • However, some reactions can occur after several hours, particularly if the allergen causes a reaction after it has been eaten.
  • The patient may receive skin or blood allergy tests, particularly if a specific allergen is suspected and available for testing.
  • It may disappear on its own when the allergen that caused it is removed.
  • The discovery makes shrimp one of a few allergenic foods for which the actual allergen has been purified and identified.
  • allergen immunotherapy: a practice parameter second update.
  • The products contain egg, an allergen, which is not noted on the label.
British Dictionary definitions for allergen


any substance capable of inducing an allergy
Derived Forms
allergenic, adjective
allergenicity, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Cite This Source
Word Origin and History for allergen

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

Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
allergen in Medicine

allergen al·ler·gen (āl'ər-jən)

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

  2. See antigen.

al'ler·gen'ic (-jěn'ĭk) adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source
allergen in Science
A substance, such as pollen, that causes an allergic reaction.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
Cite This Source

Word of the Day

Difficulty index for allergen

Some English speakers likely know this word

Word Value for allergen

Scrabble Words With Friends

Nearby words for allergen