Deficiency vs Impairment

When to use each in English, with meaning, register, and examples.

 DeficiencyImpairment
MeaningNot having enough of something you need.The condition of having a weakness or loss of ability.
Registerformalformal
CEFR levelC1-
Part of speechnoun
Usage notesUsed in medical, scientific, or formal contexts. Avoid using in casual conversation. It's appropriate when discussing health issues like vitamin deficiency.Used in medical and legal contexts to refer to loss of function or ability. Avoid in casual conversation.

Frequently asked questions: Deficiency vs Impairment

What's the difference between "Deficiency" and "Impairment"?

"Deficiency" means: Not having enough of something you need. "Impairment" means: The condition of having a weakness or loss of ability.

When should I use "Deficiency" and "Impairment"?

"Deficiency" is formal; "Impairment" is formal.

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