tetra
noun
any of several tropical, freshwater fishes of the family Characidae, often kept in aquariums.
tetra
1 American
[te-truh]
/ ˈtɛ trə /
noun
-
tetras
plural
tetra-
2
American
tetra
1
British
/ ˈtɛtrə /
noun
tetra-
2
British
combining form
Usage
What does tetra- mean? Tetra- is a combining form used like a prefix meaning “four.” It is used in a great many scientific and other technical terms. In chemistry, tetra- is specifically used to indicate four atoms or four groups of atoms in compounds, e.g., tetrachloride. Tetra- ultimately comes from the Greek téttares, meaning “four.” The name of the classic video game Tetris is based in part on this Greek root. Find out the rest of the story of how Tetris got its name here. The Latin word for “four” is quattor, source of the combining forms quadr-, quadra-, quadri-, and quadru-. Learn about their specific applications in our Words That Use articles for the forms. What are variants of tetra-?When combined with words or word elements that begin with a vowel, tetra- becomes tetr-, as in tetracid.
Other Word Forms
Noun Inflected Forms
Etymology
Origin of tetra1
1930–35; shortening of New Latin Tetragonopterus former genus name. See tetragon, -o-, -pterous
Origin of tetra-2
< Greek, combining form of téttara, neuter of téttares four
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:
To study the evolution of smell-driven behaviours in a laboratory setting, the researchers chose two closely related fish of the Mexican tetra species -- the blind cave-dwelling subtype, and its sighted surface river-dwelling counterpart.
From Science Daily ● Dec. 19, 2023
When floods carried some Mexican tetra river fish, Astyanax mexicanus, into about 30 different caves, other fish of the same species remained at the surface, providing a natural study in contrasting evolutionary paths.
From Washington Post ● Feb. 2, 2023
The banded tetra feeds largely on insects from the terrestrial ecosystem and then excretes phosphorus into the aquatic ecosystem.
From Textbooks ● Sep. 6, 2018
I will not only go to New York and hang out behind the counter and mess with people, but “The Original Soup Man” is now in supermarkets in tetra pack cartons.
From Washington Times ● Jan. 11, 2017
Three insecticides were tested at Anna, Illinois, Lindane, parathion, and tetra ethyl pyro phosphate, known as TEPP.
From Northern Nut Growers Association Report of the Proceedings at the 43rd Annual Meeting Rockport, Indiana, August 25, 26 and 27, 1952 by Northern Nut Growers Association
O, usually divalent, but tetravalent and possibly hexavalent in oxonium and other salts; S, Se, Te, di-, tetra- and hexa-valent; Cr, di-, tri- and hexa-valent; Mo, W, di-, tri-, tetra-, penta- and hexa-valent.
From Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" by Various
B, trivalent; Al, trivalent, but possibly also tetra- or penta-valent; Ga, divalent and trivalent; In, mono-, di- and tri-valent; Tl, monovalent and trivalent.
From Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" by Various
The number of NO3 groups which unite with the cellulose molecule under these conditions depends upon the temperature, pressure, etc., employed during the nitration process; di-, tri-, tetra-, penta-, and hexanitrates are all known.
From The Chemistry of Plant Life by Thatcher, Roscoe Wilfred
This group spans more than 10,000 species, from catfish to aquarium favorites such as tetras and zebrafish.
From Science Daily ● Nov. 3, 2025
I didn’t see the usual darting of neon tetras, and the guppy tanks were all dark.
From "Please Ignore Vera Dietz" by A.S. King
It seemed expedient to provide something substantial, as all stood in need of nourishment, so two tetras were quickly plucked, spitted upon a stick, and placed to roast before at blazing fire.
From The Mysterious Island by White, Stephen W.
Pencroff had found in the grass half-a-dozen tetras nests, with two or three eggs in each.
From The Mysterious Island by White, Stephen W.
Even the couroucous were invisible, and it seemed likely that the sailor would be obliged to return to that swampy place where he had fished for tetras with such good luck.
From The Mysterious Island by White, Stephen W.
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.
