allergy
Americannoun
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an abnormal reaction of the body to a previously encountered allergen introduced by inhalation, ingestion, injection, or skin contact, often manifested by itchy eyes, runny nose, wheezing, skin rash, or diarrhea.
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hypersensitivity to the reintroduction of an allergen.
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Informal. a strong dislike or aversion, as toward a person or activity.
He has an allergy to hard work.
noun
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a hypersensitivity to a substance that causes the body to react to any contact with that substance. Hay fever is an allergic reaction to pollen
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informal aversion
he has an allergy to studying
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An abnormally high immunologic sensitivity to certain stimuli such as drugs, foods, environmental irritants, microorganisms, or physical conditions, such as temperature extremes. These stimuli act as antigens, provoking an immunological response involving the release of inflammatory substances, such as histamine, in the body. Allergies may be innate or acquired in genetically predisposed individuals. Common symptoms include sneezing, itching, and skin rashes, though in some individuals symptoms can be severe.
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See also anaphylactic shock
Other Word Forms
Noun Inflected Forms
Etymology
Origin of allergy
1910–15; < Greek áll ( os ) other + -ergy < Greek -ergia, equivalent to érg ( on ) activity + -ia -y 3
Explanation
An allergy is a physical reaction to some specific food or substance. If you have an allergy to cats, they'll make you itchy and swollen no matter how much you love to pet them. If you have an allergy, it can range from mild — itchy eyes in the springtime — to serious — being unable to breathe after eating a peanut. People have allergies to all kinds of things, including milk, chocolate, corn, dust, mold, and just about any kind of animal you can think of. Allergy was originally Allergie, a German word invented by a doctor who combined the Greek roots allos, "other, different, or strange," and ergon, "activity."
Vocabulary lists containing allergy
National Nurses Week: Medical Branches and Conditions
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This Week In Words: Current Events Vocab for February 6–12, 2021
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This Week in Words: Current Events Vocabulary for July 29–August 4, 2023
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
She receives weekly allergy shots to live with Jaboo, who eats a specialized allergen-reducing diet.
From The Wall Street Journal ● Jul. 6, 2026
Alpha-gal syndrome is a potentially life-changing allergy linked to the lone-star tick.
From The Wall Street Journal ● Jun. 26, 2026
Warmer days often means greater pollen emission and if sunny, dry and breezy they are notoriously the trickiest days for allergy sufferers.
From BBC ● Jun. 14, 2026
Mum Katie Hutt, 46, is hoping Yann will be in remission by the time he is in secondary school after enrolling on an allergy elimination programme in California, which costs them £30,000 a year.
From BBC ● Jun. 13, 2026
The anticipation was contagious, and my curiosity eventually outweighed my allergy to plunging to my death.
From "Tristan Strong Punches a Hole in the Sky" by Kwame Mbalia
An unhealthy microbial balance has been associated with a higher risk of allergies, depression, anxiety, and neurodegenerative diseases, including Alzheimer's disease.
From Science Daily ● Jul. 10, 2026
Approved by the Food and Drug Administration in 2024 for all food allergies, the drug helps reduce allergic reactions after accidental exposures.
From The Wall Street Journal ● Jun. 25, 2026
Raw dairy, his farm has claimed, could cure, treat or prevent myriad diseases and ailments, from diabetes and ear infections to allergies, eczema and arthritis.
From Salon ● Jun. 22, 2026
UK-wide data shows more than 25,000 hospital admissions annually for allergies and anaphylaxis in England - double the number seen 20 years ago - with roughly 1,000 in Wales.
From BBC ● Jun. 13, 2026
All those stories I’d heard about peanut butter allergies and how babies shouldn’t have it until they were older.
From "Harbor Me" by Jacqueline Woodson
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
