plural noun
ar·​chaea | \ är-ˈkē-ə How to pronounce archaea (audio) \

Definition of archaea

: usually single-celled, prokaryotic microorganisms of a domain (Archaea) that includes methanogens and those of harsh environments (such as acidic hot springs, hypersaline lakes, and deep-sea hydrothermal vents) which obtain energy from a variety of sources (such as carbon dioxide, acetate, ammonia, sulfur, or sunlight) Characterized under the heading archaea, these creatures have an amazing lineage that extends deep in the geologic record to the twilight of Earth's organic origins.— Todd Wilkinson … although archaea organize their DNA much as bacteria do (they also have no cell nucleus, for example), many aspects of the way the DNA gets processed are distinctly different. Instead, the processing is more similar to what goes in within eukaryotic cells.— Olivia Judson Many of the archaea are thermophilic. These amazing "extremophiles" eke out a living in environments in which no other organism can survive.— David W. Wolfe — see archaean — compare bacterium, eukaryote

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Other Words from archaea

archaeal \ är-​ˈkē-​əl How to pronounce archaeal (audio) \ adjective
Hot springs in Yellowstone National Park have revealed head-spinning levels of archaeal diversity—including a pair of organisms that are the most primitive forms of life alive today. — Carl Zimmer … the archaeal proteins responsible for several crucial cellular processes have a distinct structure from the proteins that perform the same tasks in bacteria. — W. Ford Doolittle

Examples of archaea in a Sentence

Recent Examples on the Web That’s because microbes like bacteria and archaea coat surfaces in a sticky layer, a biofilm, that functions as a chemical and physical come-hither call for larger creatures such as barnacles and coral, Dr. Hamdan said. Katherine Kornei, New York Times, "Microbes Point the Way to Shipwrecks," 21 Feb. 2020 Collectively, this consortium of bacteria, archaea, fungi and viruses are called our microbiota. Michelle Sconce Massaquoi, The Conversation, "Why hand-washing really is as important as doctors say," 3 Mar. 2020 Once software had assembled the short sequences of the original survey into longer fragments, the researchers checked for gene similarities to identify whether the fragment came from bacteria, complex cells, archaea, or viruses. John Timmer, Ars Technica, "Giant viruses may be attacking the microbes in our guts," 13 Feb. 2020 But by 2015, the researchers had isolated an intriguing new species of archaea. Carl Zimmer, New York Times, "This Strange Microbe May Mark One of Life’s Great Leaps," 15 Jan. 2020 The point of contention is over tiny trace amounts of DNA found in the pool that belong to a category of life called archaea, or archaebacteria. Caroline Delbert, Popular Mechanics, "Scientists Are Fighting Over One of the Hottest Places on Earth," 15 Nov. 2019 Called archaea, the microbes may be the ancestral link between complex and single-celled life. Danielle Hall, Smithsonian, "Eighteen Things We’ve Learned About the Oceans in the Last Decade," 20 Apr. 2010 Pyroaerobiology, a new field of science with a badass name, seeks to understand how colonies of bacteria, fungi, archaea, and viruses are swept up in smoke. Jennifer Leman, Popular Mechanics, "How This Researcher Invented an Entirely New—and Entirely Badass—Field of Science," 20 Dec. 2019 Moreover, Schleper said, the methods used to survey microbial diversity aren’t well suited to detecting archaea in general. Quanta Magazine, "Mongrel Microbe Tests Story of Complex Life," 29 Oct. 2015

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'archaea.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of archaea

1990, in the meaning defined above

History and Etymology for archaea

New Latin, from Greek archaios

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The first known use of archaea was in 1990

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Cite this Entry

“Archaea.” Dictionary, Merriam-Webster, Accessed 11 Jul. 2020.

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More Definitions for archaea


noun plural
ar·​chaea | \ är-ˈkē-ə How to pronounce archaea (audio) \

Medical Definition of archaea

1 capitalized : a domain of primitive single-celled prokaryotic microorganisms including methane-producing forms and others that thrive in extremely salty or hot, often acidic environments They are largely Archaea, a domain of life first identified 20 years ago …— Charles W. Petit and Laura Tangley, U.S. News & World Report, 8 Nov. 1999
2 : microorganisms of the domain Archaea Many of the archaea are thermophilic.— David W. Wolfe, Wilson Quarterly, Spring 2001

Other Words from archaea

archaeal \ är-​ˈkē-​əl How to pronounce archaeal (audio) \ adjective
Despite the morphological resemblance of archaea to bacterial cells (e.g., lack of a nuclear membrane), many archaeal processes, such as transcription, are much more similar to those of eukaryotes. — Ken F. Jarrell, Bioscience, 1 July 1999

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