/ Dictionary / Index S split second: Meaning and Definition of Find definitions for: split' sec'ond Pronunciation: [key] a fraction of a second. an infinitesimal amount of time; instant; twinkling. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. split screen split spindle Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language