alga

American

[al-guh] / ˈæl gə /

noun

any organism belonging to one of the numerous groups of algae.

alga Scientific

/ ăl′gə /

Any of various green, red, or brown organisms that grow mostly in water, ranging in size from single cells to large spreading seaweeds. Like plants, algae manufacture their own food through photosynthesis and release large amounts of oxygen into the atmosphere. They also fix large amounts of carbon, which would otherwise exist in the atmosphere as carbon dioxide. Algae form a major component of marine plankton and are often visible as pond scum and blooms in tidal pools. Land species mostly live in moist soil and on tree trunks or rocks. Some species live in extreme environments, such as deserts, hot springs, and glaciers. Although they were once classified as plants, the algae are now considered to be protists, with the exception of the cyanobacteria, formerly called blue-green algae. The algae do not form a distinct phylogenetic group, but the word alga serves as a convenient catch-all term for various photosynthetic protist phyla, including the green algae, brown algae, and red algae.

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alga algae

The purpose of this brilliance remains unclear, especially because the alga lives too deep for it to be related to photosynthesis.

From Science Magazine ● May 21, 2024

The alga, native to the Southern Ocean, starts as a single-cell that can transform into millimeter scale colonies.

From Science Daily ● Feb. 5, 2024

Blue-green algae is not actually an alga but rather a type of bacteria called cyanobacteria.

From BBC ● Jul. 10, 2023

This is the first recorded example of an alga practicing an aquatic equivalent to pollination.

From Scientific American ● Jul. 28, 2022

She is curious; she wants to know the difference between an alga and a lichen, a Diplodon char- ruanus and a Diplodon delodontus.

From "All the Light We Cannot See" by Anthony Doerr

Familiar examples include amoebas, various algae, and diatoms, which are microscopic organisms often found in aquatic environments.

From Science Daily ● Oct. 8, 2026

“Root systems protect Lake Tahoe’s clarity by stabilizing soils that could erode, and uptaking nutrients that would feed algae in the lake,” Cowen wrote in an email.

From Los Angeles Times ● Sep. 19, 2026

Think mushroom leather, spider-silk filaments, membranes of algae.

From The Wall Street Journal ● Sep. 19, 2026

Shortly after reopening, the water turned green with algae.

From Salon ● Sep. 12, 2026

And he came at last to the outer barrier where the long leathery brown algae hung down into the water.

From "Cannery Row" by John Steinbeck

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