/ Dictionary / Index D diastole: Meaning and Definition of Find definitions for: di•as•to•le Pronunciation: (dī-as'tl-ē", -tl-ē), [key] — n. the normal rhythmical dilatation of the heart during which the chambers are filling with blood. Cf. systole (def. 1). the lengthening of a syllable regularly short, esp. before a pause or at the ictus. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: diastole (Thesaurus) diastereomer diastolic 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