not watchful or alert; lacking in vigilance: an irresponsible and watchless sentry.
having no watch; without guards or sentries: We welcomed the watchless nights of peacetime.

Origin of watchless

First recorded in 1615–25; watch + -less
Related formswatch·less·ness, noun Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019