To impair something is to weaken it or damage it so it does not work as well as before. It can refer to physical abilities, mental functions, or the quality of objects or systems.
From Old French "empairier" meaning "to make worse," from Vulgar Latin *"impejorare," from Latin "peior" (worse). The word has long been tied to the idea of worsening a condition or ability.
Impairment isn’t always visible—someone can look fine yet have seriously impaired hearing, memory, or attention. A little impairment in a key system, like judgment while driving, can have far bigger consequences than it seems.
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