IPA: /ɪmˈpɛə.mənt/
KK: /ɪmˈpɛr.mənt/
A condition in which something is weakened or damaged, often affecting its function or ability.
The doctor diagnosed her with a hearing impairment that made it difficult for her to understand conversations.
Impairment is formed from "im-" (meaning not) and "pair" (from Latin "parare", meaning to make equal or prepare) and the suffix "-ment" (indicating the action or result of a process). The word refers to the condition of being made less than equal or whole, indicating a loss of function or ability.
Think of 'not' being added to 'make equal' — that's why impairment means a condition where something is not functioning at its full capacity.