Definitions

1. noun

A free-swimming, usually colonial, organism, especially a small, usually flagellated, form of algae or protozoan.

“Some plankters in the ocean are bioluminescent, emitting a blue glow when disturbed.”

2. verb

To move or float suspended in water, typically just below the surface, especially in a casual or aimless manner.

“The leaves on the pond seemed to plankter across its surface.”