allergy

allergy — noun

1. a health problem in which your body reacts in a harmful way — for example with a

1.nounB1
Definition

a health problem in which your body reacts in a harmful way — for example with a rash, sneezing, or trouble breathing — when you eat, touch, or breathe in something most people are fine with.

Example

Amara has a serious allergy to peanuts and always carries her medicine.

allergy + to + noun (food trigger)

The doctor confirmed that little Hiro's rash was caused by a milk allergy.

compound: [substance] + allergy

Common collocations
  • severe allergy
  • food allergy
  • peanut allergy
  • develop an allergy
  • trigger an allergy
  • suffer from an allergy
Synonyms
  • hypersensitivity

    technical medical term; used in clinical writing rather than daily speech

  • intolerance

    overlapping but narrower — usually digestive, e.g. lactose intolerance; not the same as a true immune reaction

Grammar Patterns

allergy + to + noun

Usage Note

Almost always paired with the preposition 'to' to name the trigger (allergy to nuts/pollen/cats). Also forms common compound nouns: peanut allergy, dust allergy, food allergy.

Common Mistakes

I have allergy of cats.
I have an allergy to cats.
use 'to', not 'of', and add the article 'an'.
She is allergy to milk.
She is allergic to milk.
'allergy' is the noun; the adjective is 'allergic'.

Word family

  • allergic
    adjectiveB1
  • allergen
    nounC1
  • allergist
    nounC2
  • hypoallergenic
    adjectiveC2

Synonym discussion

Sense: noun/1

All four words describe an unusual bodily response to something, but they are used in different ways. 'Allergy' is the everyday word and refers to a true immune reaction — the body treats a harmless substance as dangerous and may cause sneezing, rashes, or even shock. 'Hypersensitivity' is the formal medical term doctors use in reports; it covers allergies but also other over-reactions of the immune system. 'Intolerance' is narrower and usually digestive: lactose intolerance, for example, causes stomach pain but does not involve the immune system. 'Sensitivity' is the mildest and vaguest, often meaning a person reacts to something more strongly than average without a clear medical cause. So you might say 'a peanut allergy' but 'a sensitivity to bright light'.

allergy ↗hypersensitivityintolerancesensitivity ↗

Common collocations

Nouns

  • food allergy
  • peanut allergy
  • skin allergy
  • dust allergy
  • pollen allergy

Adverbs

Phrases

  • develop an allergy
  • trigger an allergy
  • suffer from an allergy
  • test for allergies

Prepositions

  • allergy to
  • allergy in (children)

Etymology

GreekGermanEnglish

Coined in 1906 by the Austrian doctor Clemens von Pirquet, who joined the Greek roots 'allos' meaning 'other' or 'different' and 'ergon' meaning 'work' or 'reaction'. He needed a name for the strange way some patients reacted differently to a substance after a first contact with it. The word entered English from German 'Allergie' soon after, and the broader figurative use ('an allergy to hard work') appeared by the 1940s.