/ Dictionary / Index A April Fools' Day: Meaning and Definition of Find definitions for: A'pril Fools'' Day" Pronunciation: [key] April 1, a day when practical jokes or tricks are played on unsuspecting people. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. April fool a priori Related Content Daily Word Quiz: mamba Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language