/ Dictionary / Index H holy grass: Meaning and Definition of Find definitions for: ho'ly grass" Pronunciation: [key] any of several fragrant grasses of the genus Hierochloë, esp. H. odorata, the vanilla grass. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Holy Grail Holyhead 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