Simple Definition of plankton

from our Learner's Dictionary

plankton

noun

ˈplæŋktən

: the very small animal and plant life in an ocean, lake, etc.

fish that feed mainly on plankton

—often used with a plural verb

the plankton that are eaten by fish

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“Plankton.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/plankton. Accessed 21 Jun. 2026.

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