sleepwalker
UK[ˈsliːpˌwɔːkə]US[ˈsliːpˌwɔːkər]
n
a person who walks around while they are asleep
Morpheme Breakdown
sleep
walk
er
sleep
to rest in sleep
walk
to move on foot
er
person who does
Etymology
the word sleepwalker is a transparent compound formed within english from its germanic roots. the first element, sleep, descends from the old english verb slǣpan, which has cognates across germanic languages and traces back to a proto-indo-european root meaning to be slack or loose, a state associated with rest. the second element, walk, originates from old english verbs connoting rolling or moving, which later specialized to mean moving on foot. the agent suffix er, also of old english origin, is added to form a noun meaning one who does something. thus, sleepwalker literally and logically denotes a person who performs the action of walking while in the state of sleep, a phenomenon now understood as somnambulism.
Analysis
Structure: sleep (to rest in sleep) + walk (to move on foot) + er (person who does)
sleep: from old english slǣpan (to sleep), germanic origin. functional role: root, indicating the state of being asleep.
walk: from old english wealcan (to roll, toss) and wealcian (to roll up, curl), germanic origin. functional role: root, indicating the action of moving on foot.
er: from old english -ere, agent noun suffix, germanic origin. functional role: suffix, denoting a person who performs the action.
Examples
the old house had a reputation for being haunted, but the strange noises were just caused by a sleepwalker.
as a chronic sleepwalker, he sometimes woke up in the kitchen or even outside.
the film featured a terrifying villain who was a murderous sleepwalker.