somnambulism \som-NAM-byuh-liz-uhm, suhm-\,
noun:
sleepwalking.
...they shared with him an alert interest in oddities of human behavior, attentive to evidence of madness, delusions, dreams, manias, and somnambulism.
-- Charles Brockden Brown, "Edgar Huntly; or, Memoirs of a Sleep-Walker," 1799
Yet there must have been some connection between those episodes of somnambulism and the increasingly frequent, everyday cruelties that Malcolm Kennedy was imposing upon me at exactly that same time...
-- John Burnside, "The Devil's Footprints," 2007
Somnambulism came to English in the late 1700s from the Latin somnus + ambulare literally meaning "sleep" + "to walk."
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