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algae

American  
[al-jee] / ˈæl dʒi /

plural noun

singular

alga

  1. 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, ˈælɡəl /

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.

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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

  • algal adjective

Etymology

Origin of algae

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

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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.

That iron would fuel blooms of microscopic algae, which absorb heat trapping carbon dioxide as they grow.

From Science Daily

Turtles swim into the mouth of the river, in the Long Beach-Seal Beach area, and then just hang out and eat algae.

From Los Angeles Times

Aside from potential health harms to humans, the tiny particles could be damaging to algae as well as crop harvests.

From The Wall Street Journal

Its larvae inhabit damp mats of moss and algae along the Antarctic Peninsula.

From Science Daily

The other is microscopic algae that live inside the coral's tissues and use sunlight to produce energy, which feeds the coral.

From Science Daily

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

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.