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

Moreover, the alga cannot easily move away from the light like animals and humans can.

From Science Daily ● Nov. 18, 2024

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

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

The neurotoxin can be produced by an algae called Pseudo-nitzschia, and “the warmer the ocean is, the more algae,” McGuire said.

From Los Angeles Times ● Aug. 10, 2026

Kimberly-Clark identified hesperaloe as a top contender among 70 candidates for potential new sources of fiber, including wheat straw, leftover corn, chicken feathers, seaweed and algae.

From The Wall Street Journal ● Aug. 7, 2026

Except, of course, keeping a massive outdoor pool pristine and leak-free is complicated, and Trump’s renovation flopped: The algae came back, joined by pieces of the pool’s new lining floating in the water.

From Slate ● Aug. 4, 2026

Blue-green algae, also known as cynobacteria, produces a layer of scum that sits on the water and is toxic to wildlife.

From BBC ● Aug. 4, 2026

They carried lice and ringworm and leeches and paddy algae and various rots and molds.

From "The Things They Carried" by Tim O'Brien

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