ˈplüstən noun
( -s )
Etymology: International Scientific Vocabulary pleus- (from Greek pleusis sailing, from plein to sail) + -ton (as in plankton ) — more at flow
: small but macroscopic floating organisms that form mats or layers on or near the surface of a body of water, that usually include floatingalgae (as spirogyras), small floating spermatophytes (as the duckweeds), and associated small animals, and that usually exclude anchored plants and larger floating spermatophytes (as the water hyacinth) — compare neuston