'allergy' originates from Greek, specifically the word 'allergia,' where 'allos' meant 'other' and 'ergon' meant 'work.'

'allergia' transformed into the German word 'Allergie,' and eventually became the modern English word 'allergy' through medical terminology.

Initially, it meant 'a different reaction,' but over time it evolved into its current meaning of 'a hypersensitive reaction to a substance.'