/ Dictionary / Index K keystone: Meaning and Definition of Find definitions for: key•stone Pronunciation: (kē'stōn"), [key] — n. the wedge-shaped piece at the summit of an arch, regarded as holding the other pieces in place. something on which associated things depend: the keystone of one's philosophy. Also calledSee(def. 1). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: keystone (Thesaurus) key station Keystone comedy Related Content Daily Word Quiz: cur Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language