IPA: //ˈsliːpˌwɔːkər//
KK: /ˈsliːpˌwɔːkər/
A person who walks around while they are asleep, often without being aware of it.
Last night, I saw my brother as a sleepwalker wandering through the house.
Sleepwalker → It is formed from "sleep" (from Old English *slǣpan*, meaning to rest or be in a state of sleep) and "walker" (from Old English *wealcan*, meaning to move or walk). The word describes a person who walks while in a state of sleep.
Imagine someone who is 'resting' ('sleep') but still 'moving' ('walker') — that's why a sleepwalker is someone who walks while they are asleep.