/ Dictionary / Index P pleuston: Meaning and Definition of Find definitions for: pleus•ton Pronunciation: (pl'stun, -ston), [key] — n. Biol. a buoyant mat of weeds, algae, and associated organisms that floats on or near the surface of a lake, river, or other body of fresh water. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. pleuropneumonialike organism Pleven Related Content Daily Word Quiz: deleterious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language