/ Dictionary / Index I index number: Meaning and Definition of Find definitions for: in'dex num"ber Pronunciation: [key] — Statistics. Statistics. a quantity whose variation over a period of time measures the change in some phenomenon. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. index-link index of leading indicators Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language