Definition of allergic

The word "allergic" has its roots in the ancient Greek language. The term "allergia" was coined in 1906 by Austrian pediatrician Victor von Czerny, who derived it from the Greek words "allos" meaning "other" and "ergon" meaning "work" or "action". This was in response to the work of businessman Clemens von Pirquet, who had discovered that some people developed severe reactions to small amounts of substances like perfume, medicine, and pollen. Pirquet observed that these reactions were not due to the substance itself, but to the individual's reaction to it. Von Czerny combined Pirquet's concept with the Greek words to create "allergia", meaning "other reaction" or "unusual reaction". The term "allergic" is a direct adaptation of "allergia" and has been used in English since the early 20th century to describe these unusual and often debilitating reactions to substances.