/ Dictionary / Index G ground rule double: Meaning and Definition of Find definitions for: ground' rule" dou'ble Pronunciation: [key] — Baseball. Baseball. a safe hit ruled for two bases according to the rules of a particular stadium, as when a fly ball bounces once in the outfield and then clears a fence. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ground rule groundsel Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language