tet·​ra | \ ˈte-trə How to pronounce tetra (audio) \

Definition of tetra

 (Entry 1 of 2)

: any of numerous small often brightly colored South American characin fishes often bred in tropical aquariums
variants: or tetr-

Definition of tetra- (Entry 2 of 2)

1 : four : having four : having four parts tetravalent
2 : containing four atoms or groups (of a specified kind) tetrachloride

Examples of tetra in a Sentence

Recent Examples on the Web: Noun

As space and food decline over the year, and the concentration of predators increases, most of the tetras will die, Dowd says. Harrison Takoff, Smithsonian, "Why You Can Walk Into a Store and Buy a Nearly Extinct Animal," 2 Apr. 2018 In the meantime, the black headwater catfish and silvery Mexican tetras will have the 3.5 million gallon pool all to themselves. John Maccormack, San Antonio Express-News, "Rash of earthquakes prompts fear of oil boom in Balmorhea," 15 June 2018 Mexican tetra swam from surface waters into their caves around 1.5 million years ago. Diana Gitig, Ars Technica, "An evolutionary adaptation that doesn’t directly rely on new mutations," 1 June 2018 By the Fifties the medical research being done was not kind to that fuel, but because of the work of those producing tetra ethyl lead and gasoline, and our love of mobility, the public was blissfully unaware of the serious long term health issues. star-telegram, "Gasoline: Pump Us Up?," 28 Apr. 2018 She was born with tetra-Amelia syndrome, a rare disorder characterized by the absence of limbs. Jonathan Wolfe, New York Times, "Painting With Her Feet, an Artist ‘Expresses Who I Am’," 24 Dec. 2017 There’s not just electric eels; there are at least a dozen tanks filled with different catfish, tetras, piranhas and the electric field-generating, ray-finned knifefish—black ghost, bluntnose and elephant nose. Natalie Escobar, Smithsonian, "The Shocking World of Electric Fishes," 20 Oct. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'tetra.' 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 tetra


1931, in the meaning defined above

History and Etymology for tetra


by shortening from New Latin Tetragonopterus, former genus name, from Late Latin tetragonum quadrangle + Greek pteron wing — more at tetragonal, feather

Combining form

New Latin, from Greek; akin to Greek tettares four — more at four

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The first known use of tetra was in 1931

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More from Merriam-Webster on tetra

Britannica.com: Encyclopedia article about tetra

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a shady place in a garden or forest

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