/ Dictionary / Index O Old Faithful: Meaning and Definition of Find definitions for: Old' Faith'ful Pronunciation: [key] one of the best known geysers of Yellowstone National Park. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. oldest oldfangled Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language