To impair something means to damage it or make it work less well than it should. When fog impairs a driver's vision, it becomes harder to see the road clearly. When a sprained ankle impairs your ability to run, your leg still works but not at full strength.

The word suggests partial damage rather than complete destruction. A scratched lens might impair your view through a microscope without making it completely useless. Loud music can impair your hearing temporarily, making sounds seem muffled for a while afterward.

You'll often hear about things that impair judgment, like how being very tired can impair your ability to make good decisions, or how strong emotions might impair someone's thinking during an argument. The key idea is that something still functions but not as effectively as normal.

An impairment is the actual damage or limitation itself. Someone with a hearing impairment might use a hearing aid. A visual impairment might mean someone needs glasses or uses a cane to navigate. These impairments describe real challenges that affect how certain abilities work.