/ Dictionary / Index P ppm: Meaning and Definition of Find definitions for: ppm Pronunciation: [key] parts per million. pulse per minute. p.p.m. Pronunciation: [key] parts per million. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. PPLO PPO Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language