/ Dictionary / Index S sleeper seat: Meaning and Definition of Find definitions for: sleep'er seat" Pronunciation: [key] a seat, as on an airplane, that can be extended horizontally to permit sleeping. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. sleeper sleep-in 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