/ Dictionary / Index E extrasystole: Meaning and Definition of Find definitions for: ex•tra•sys•to•le Pronunciation: (ek"stru-sis'tu-lē), [key] — n. Pathol. a premature contraction of the heart, resulting in momentary interruption of the normal heartbeat. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: extrasystole (Thesaurus) extrasolar extraterrestrial Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language