green algae

American

plural noun

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

green algae British

plural noun

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of green algae

First recorded in 1900–05

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The answer, for that sample, was: mostly Desmodesmus, a green algae that gobbles up phosphorus and nitrogen.

From Slate • Jun. 27, 2026

Instead of the previous blue-green algae, the new green algae is "just taking over," Paerl said.

From Barron's • Jun. 21, 2026

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

It started with a soft green algae that clung to the life jackets.

From "Life of Pi" by Yann Martel

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023