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Synonyms

algae

American  
[al-jee] / ˈæl dʒi /

plural noun

  • alga
    singular
  1. An image of the word algae as defined by any of numerous groups of chlorophyll-containing, mainly aquatic, eukaryotic organisms ranging from microscopic single-celled forms to multicellular forms 100 feet (30 meters) or more long, distinguished from plants by the absence of true roots, stems, and leaves and by a lack of nonreproductive cells in the reproductive structures: classified into the six phyla Euglenophyta, Crysophyta, Pyrrophyta, Chlorophyta, Phaeophyta, and Rhodophyta.

    Microbiology. any of numerous groups of chlorophyll-containing, mainly aquatic, eukaryotic organisms ranging from microscopic single-celled forms to multicellular forms 100 feet (30 meters) or more long, distinguished from plants by the absence of true roots, stems, and leaves and by a lack of nonreproductive cells in the reproductive structures: classified into the six phyla Euglenophyta, Crysophyta, Pyrrophyta, Chlorophyta, Phaeophyta, and Rhodophyta.


algae British  
/ ˈældʒiː /

plural noun

  1. unicellular or multicellular organisms formerly classified as plants, occurring in fresh or salt water or moist ground, that have chlorophyll and other pigments but lack true stems, roots, and leaves. Algae, which are now regarded as protoctists, include the seaweeds, diatoms, 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

algae Cultural  
  1. Primitive organisms that contain chlorophyll but do not have structures, such as xylem and phloem, to transport fluids. Algae sometimes contain only a single cell, and nowadays they are not considered members of the plant kingdom.


Discover More

Algae supply a considerable part of the world's oxygen.

The most familiar algae are the greenish scum that collects in still water.

Other Word Forms


Etymology

Origin of algae

First recorded in 1790–1800; from New Latin, plural of Latin alga “seaweed”


Compare meaning

How does algae compare to similar and commonly confused words? Explore the most common comparisons:


Explanation

Ever walk in the ocean and feel your feet slipping and sliding along the rocks? That slimy green stuff under your feet is algae, a nonflowering plant that grows in the water and has no stems, roots, or leaves. Algae is actually the plural form of the word alga, which in Latin means, you guessed it: "seaweed." Algae isn't just something gross looking floating on the water. It's actually important in aquatic ecology because the tiny organisms that live suspended in algae are the food base for most marine food chains.

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Vocabulary lists containing algae

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.

See Examples For:

During droughts, algae blooms have turned waterways bright green.

From Los Angeles Times ● Oct. 30, 2026

The researchers examined concentrations of a biomarker known as IP25, which is produced by algae associated with sea ice.

From Science Daily ● Oct. 26, 2026

The five-term senator said the categories of products receiving exemptions include corrugated paper cartons, plastic boxes, plastic bags, refrigeration and freezing equipment, packing and wrapping machinery, and seaweed and algae products.

From MarketWatch ● Oct. 23, 2026

"Whenever the bad algae grows more, because of the nutrients in the lakes, it will release the various toxins that are very harmful for humans."

From BBC ● Oct. 23, 2026

When she waded into the swamp, the reeds twisted themselves into a boat, and she climbed aboard, floating across the deep red of the algae coating the water.

From "The Girl Who Drank the Moon" by Kelly Barnhill

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

From Science Daily ● Nov. 18, 2024

In this study, pyrenoid-associated proteins in a marine chlorarachniophyte alga were identified through a proteomic approach.

From Science Daily ● Mar. 1, 2024

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

From BBC ● Jul. 10, 2023

Myriam Valero, a population geneticist at CNRS, the French national research agency, has been studying the genetics of the red alga Gracilaria gracilis for many years in the tidepools of Europe.

From Science Magazine ● Jul. 27, 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

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