/ Dictionary / Index P plagio-: Meaning and Definition of Find definitions for: plagio- Pronunciation: [key] a combining form meaning “oblique,” used in the formation of compound words: plagioclase. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. plagiary plagiocephaly Related Content Daily Word Quiz: deleterious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language