What does allergy mean?
An allergy is a condition in which the body's immune system overreacts to a substance that is ordinarily harmless—pollen, dust mites, certain foods, insect venom, or medications—producing symptoms that range from sneezing and itching to hives, swelling, and, in severe cases, life-threatening anaphylaxis. Common examples include hay fever, peanut allergies, and reactions to cat dander, and they are typically managed by avoidance, antihistamines, or emergency epinephrine. Beyond its medical meaning, the word has picked up an informal, figurative use: someone might say they have an 'allergy' to paperwork or to getting up early, signaling a strong aversion rather than a genuine immune reaction. Coined only in the early twentieth century from Greek roots meaning 'other' and 'work', the term reflects how foreign the concept once seemed. Today, allergies are among the most common chronic conditions worldwide, making 'allergy' an essential word for discussing both health and everyday dislikes.
nounA condition in which the immune system reacts abnormally to a usually harmless substance, such as pollen, certain foods, or animal dander, causing symptoms like sneezing, itching, or swelling. More generally, a strong dislike or aversion to something.
- A harmful immune response to a normally harmless substance (the medical sense).
- An informal sense of a strong dislike or aversion toward a thing or activity.
"She carries an epinephrine auto-injector because of her severe peanut allergy."
"His allergy to shellfish means he must read every menu carefully when dining out."
"I seem to have developed an allergy to early morning meetings."
The plural is standard and widely used, especially when referring to multiple sensitivities or seasonal conditions.
"Springtime allergies affect millions of people each year."
The word 'allergy' was only coined in 1906 — meaning this common word is barely older than the airplane.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of allergy
The word 'allergy' is a modern scientific coinage, introduced by Austrian pediatrician Clemens von Pirquet in 1906. He built it from Greek elements: 'allos' meaning 'other' or 'different' and 'ergon' meaning 'work' or 'activity', capturing the idea of an altered or abnormal reaction by the body. Related terms sharing the same Greek root include 'allergen', 'allergic', and 'energetic', which also derives from 'ergon'.
Related word forms
How allergy is actually used
Primarily used in medical and everyday health contexts; the figurative use (an 'allergy' to work or criticism) is informal and slightly humorous. The plural 'allergies' is common when referring to multiple sensitivities or seasonal symptoms.
Easily confused with allergy
An intolerance (such as lactose intolerance) involves difficulty digesting a substance without immune-system involvement, whereas an allergy triggers a true immune response that can be life-threatening.