Allergy

Definition

Allergy refers to a hypersensitive immune response to a normally harmless substance (an allergen), resulting in symptoms such as sneezing, itching, hives, or more severe reactions. Its plural form is allergies.

Parts of Speech

• Noun

Pronunciation

American English

• IPA: /æl.ərˈdʒi/
• Respelling: AL-er-jee

British English

• IPA: /ˈæl.ə.dʒi/
• Respelling: AL-uh-jee

Etymology

Late 19th century: from Greek allergos “altered reaction,” from allos “other” + ergon “work.”

Derivatives

• allergic (adjective)
• allergically (adverb)
• allergen (noun)
• allergist (noun)
• allergology (noun)
• allergenicity (noun)

Synonyms

• hypersensitivity
• sensitization
• reactivity

Antonyms

• tolerance
• immunity

Usage

"She discovered her allergy to shellfish after eating shrimp."

"Seasonal allergies often cause hay fever symptoms in spring."

Related Terms

• Allergen: A substance that triggers an allergic reaction.
• Anaphylaxis: A severe, potentially life-threatening allergic reaction.
• Histamine: A compound released during an allergic response.
• Immunology: The study of the immune system.
• Atopy: A genetic predisposition to develop allergic diseases.

Detailed Definitions

Noun

• An immune system reaction to a harmless substance – an exaggerated response by the immune system to pollen, dust, foods, or other allergens.
  • Example: "His allergy to bee stings caused his arm to swell."
• A specific sensitivity to an allergen – the individual phenomenon of reacting upon exposure to a particular substance.
  • Example: "Her peanut allergy requires her to carry an epinephrine injector."
• A medical condition characterized by recurring hypersensitivity – a chronic tendency to develop allergic symptoms.
  • Example: "He suffers from seasonal allergies every spring."