Impaired means damaged, weakened, or not working as well as it should. When something is impaired, it's still there but not functioning at full strength.

A person with impaired vision can see, but not clearly: they might need glasses or struggle to read small print. Someone with impaired hearing might miss parts of conversations or need people to speak louder. These conditions aren't about being completely unable to see or hear, but about those abilities being diminished.

The word applies beyond medical situations too. A computer with an impaired hard drive might work slowly or lose files. A friendship could become impaired after a serious disagreement, meaning it's damaged but not necessarily destroyed. When a storm leaves a bridge with impaired structural integrity, engineers mean the bridge is weakened and might not be safe.

Impaired often appears in the phrase “driving while impaired,” which means operating a vehicle when your judgment or reflexes are weakened. This is illegal because impaired drivers endanger everyone on the road.

The word carries a sense of something being less than it should be: not gone, not ruined beyond repair, but definitely not working right.