Breadcrumb Home > Dictionary > Index P PSD: Meaning and Definition of Find definitions for: PSD Pronunciation: [key] prevention of significant deterioration: used as a standard of measurement by the U.S. Environmental Protection Agency. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. pschent PSE TrendingHere are the facts and trivia that people are buzzing about. Ramadan and Eid al-Fitr 42 Best War Movie Quotes Current Events This Week: March 2023 Recycling Facts William Shakespeare Worst U.S. Forest Fires ✖ Related Content Daily Word Quiz: recreant Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language