/ Dictionary / Index P prime meridian: Meaning and Definition of Find definitions for: prime' merid'ian Pronunciation: [key] the meridian running through Greenwich, England, from which longitude east and west is reckoned. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. primely prime minister Related Content Daily Word Quiz: tactful Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language