/ Dictionary / Index P PIO: Meaning and Definition of Find definitions for: PIO Pronunciation: [key] — U.S. Mil. U.S. Mil. public information office. public information officer. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Pinzón piolet Related Content Daily Word Quiz: fervor Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language