green algae

American  

plural noun

1. any grass-green, chiefly freshwater algae of the phylum Chlorophyta, often growing on wet rocks, damp wood, or on the surface of stagnant water.

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green algae British  

plural noun

1. the algae of the phylum Chlorophyta, which possess the green pigment chlorophyll. The group includes sea lettuce and spirogyra

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Etymology

Origin of green algae

First recorded in 1900–05

Example Sentences

Now, because bright green algae keeps reappearing every year around this time, Toledo must always be prepared for such outbreaks.

From Salon • Aug. 16, 2025

It could also cause harmful algae to grow out of control, creating wide patches of green algae that can poison other life.

From BBC • May 21, 2025

There’s a faucet on the eastern end of the campground where water from the creek is piped, but upon my arrival, the trough where the water came out was covered in thick green algae.

From Los Angeles Times • May 13, 2025

This is thought to reflect the increasing diversity of life at this time and the evolution of the first fungi and green algae.

From Science Daily • Dec. 7, 2023

Then came a second gatehouse, larger than the first, its stones bearded with green algae.

From "A Dance with Dragons" by George R. R. Martin