PLANKTON
plankton
(noun) the aggregate of small plant and animal organisms that float or drift in great numbers in fresh or salt water
Source: WordNet® 3.1
Etymology
Noun
plankton (usually uncountable, plural planktons or plankton)
Small (often microscopic) organisms that float in the water. (A single organism is known as a plankter.)
Coordinate terms
• nekton
Source: Wiktionary
Plank"ton (plank"ton), n. [NL., fr. Gr. plagto`n, neut. of plagto`s
wandering, pla`zesqai to wander.] (Biol.)
Definition: All the animals and plants, taken collectively, which live at
or near the surface of salt or fresh waters. --Plank*ton"ic (#), a.
Source: Webster’s Unabridged Dictionary 1913 Edition