/ Dictionary / Index S sleep-in: Meaning and Definition of Find definitions for: sleep-in Pronunciation: (slēp'in"), [key] — adj. live-in (def. 1). —n. a person who sleeps in at a place of employment. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: sleep-in (Thesaurus) sleeper seat sleeping Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language