/ Dictionary / Index P psid: Meaning and Definition of Find definitions for: psid Pronunciation: [key] pounds per square inch, differential. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. psia psig 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