/ Dictionary / Index P PLSS: Meaning and Definition of Find definitions for: PLSS Pronunciation: [key] portable life support system. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. PLR plu Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language