tetra

¹

[ te-truh ]

noun

1. any of several tropical, freshwater fishes of the family Characidae, often kept in aquariums.

tetra-

²

1. a combining form meaning “four,” used in the formation of compound words:

   tetrabranchiate.

tetra

¹

/ ˈtɛtrə /

noun

1. any of various brightly coloured tropical freshwater fishes of the genus Hemigrammus and related genera: family Characidae (characins)

tetra-

²

combining_form

1. four

   tetrameter

Word History and Origins

Origin of tetra¹

1930–35; shortening of New Latin Tetragonopterus former genus name. See tetragon, -o-, -pterous

Origin of tetra²

< Greek, combining form of téttara, neuter of téttares four

Word History and Origins

Origin of tetra¹

C20: short for New Latin tetragonopterus (former genus name), from tetragon + -o- + -pterous, from Greek pteron wing

Origin of tetra²

from Greek

Example Sentences

Cavefish are cousins of the Mexican tetra river fish that flooded into underground caves over 100,000 years ago.

From Science Daily

Consultants and vendors have received most of Iowa’s spending so far, including $5.2 million to Tetra Tech, an engineering business that conducted 1,260 building assessments to identify weaknesses that projects would fix.

From Seattle Times

Some assessments emailed by Tetra Tech were lost in the spam folders of school administrators or faced several weeks or months of delays getting the state’s review and approval.

From Seattle Times

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

Through the international Dairy Hub Model, the collaboration of stakeholders that includes Tetra Pak, local dairy processors, international aid agencies and NGO’s is helping to build sustainable value chains by improving the productivity, market access, and profitability of smallholder dairy farms.

From National Geographic

Words That Use Tetra-

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.

Examples of tetra-

One example of a word you may have encountered that features tetra- is tetragon, “a polygon having four angles or sides,” such as a square or rectangle. A tetragon is also known as a quadrangle or quadrilateral.

The first part of the word, tetra-, means “four,” as we know. The -gon portion of the word may also look familiar: it is a combining form meaning “angled” or “angular,” from the Greek gōnía. Tetragon literally translates to “four-angled.”

The word tetragon comes from the Greek tetrágōnon, which uses the equivalent form of tetra- in the language.

Another geometric shape using the combining form tetra- is tetrahedron, a triangular pyramid; it’s so named because the shape is formed using four (tetra-) faces (-hedron).

You may have also heard of a tetralogy, which refers to a series of four related plays, novels, films, video games, or other media. It’s like a trilogy—plus one. Shakespeare’s so-called Henriad is an example of a tetralogy. It consists of four connected history plays: Richard II, Henry IV, Part 1, Henry IV, Part 2, and Henry V.

What are some words that use the combining form tetra-?

Many of the following words use the equivalent form of tetra- in Greek. 

• tetrabasic
• tetrabrach
• tetracycline
• tetradactyl
• tetrafluoroethylene
• tetragram
• Tetragrammaton
• tetrameter
• tetrapod
• tetrasaccharide
• tetraspore

What are some other forms that tetra- may be commonly confused with?

• tri-
• tetano-
• tera-
• terato-

Break it down!

The combining form -dactyl means “possessing fingers or toes” of the kind specified by the first part of the word. A tetradactyl is an animal with how many toes?