/ Dictionary / Index W window sill: Meaning and Definition of Find definitions for: win'dow sill" Pronunciation: [key] the sill under a window. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: windowsill (Thesaurus) window-shop windpipe Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language