al·​ler·​gen | \ ˈa-lər-jən \

Definition of allergen

: a substance (such as pollen) that induces allergy

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Other Words from allergen

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

Allergic reactions happen when your immune system overreacts to allergens, which are normally harmless, but can trigger some of us all the same., "It's Not Your Imagination — Allergy Season Is Worse Than Ever, & Here's Why," 16 May 2018 There’s the potential for drought resistance, nutritional improvements, and removal of allergens. Tamar Haspel, Vox, "The public doesn’t trust GMOs. Will it trust CRISPR?," 24 July 2018 Since 2004, food manufacturers in the U.S. have been required by law to label eight major allergens on their packaging: peanuts, tree nuts, milk, eggs, fish, shellfish, wheat and soybeans—but not sesame. Sumathi Reddy, WSJ, "FDA Considers Making Food Labels Disclose Sesame to Help Allergy Sufferers," 12 Nov. 2018 In a major win for people with allergies everywhere, Nestlé Toll House unveiled a new three-ingredient chocolate chip free of the eight major food allergens. Taylor Seely, USA TODAY, "Nestlé Toll House unveils allergen-free chocolate chips made with only 3 ingredients," 30 May 2018 For other areas of the South, peak allergens are expected to hit at the end of April, and according to AccuWeather, tree pollen allergies will be followed up with grass pollen, which should tamp down at the end of June. Sarah Gray, Time, "Brace Yourselves: Spring Allergy Season Is Coming. Here's What to Expect and How to Handle It," 11 Apr. 2018 Wheat allergy: Eight allergens are responsible for the majority of the 15 million people with food allergies and one of those is wheat, according to Hannah Drown,, "How many people really need to avoid gluten in their diet?," 3 Apr. 2018 The vacuum comes with an extra level of filtration to help get rid of pesky allergens and can be used on a ton of different surfaces like carpets, upholstery, stairs, counter tops, and hard floors. Lindsey Murray, Good Housekeeping, "This Popular Bissell Vacuum Is $60 on Amazon Today," 4 Apr. 2018 While aircraft are cleaned regularly, neither those cleanings nor the planes’ air filtration systems are designed to ensure allergens have been removed, American spokeswoman Leslie Scott said. Lauren Zumbach,, "Southwest Airlines will no longer serve peanuts, citing allergy concerns," 10 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'allergen.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of allergen

circa 1907, in the meaning defined above

History and Etymology for allergen

International Scientific Vocabulary allergy + -gen

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Statistics for allergen

Last Updated

21 Dec 2018

Look-up Popularity

Time Traveler for allergen

The first known use of allergen was circa 1907

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More Definitions for allergen



English Language Learners Definition of allergen

medical : a substance that causes an allergy


al·​ler·​gen | \ ˈa-lər-jən \

Kids Definition of allergen

: a substance that causes an allergic reaction


al·​ler·​gen | \ ˈal-ər-jən \

Medical Definition of allergen

: a substance that induces allergy inhaled allergens a suspected food allergen

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More from Merriam-Webster on allergen

Spanish Central: Translation of allergen

Nglish: Translation of allergen for Spanish Speakers

Britannica English: Translation of allergen for Arabic Speakers Encyclopedia article about allergen

Comments on allergen

What made you want to look up allergen? Please tell us where you read or heard it (including the quote, if possible).


tremendous in size, volume, or degree

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