tri-

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

   triacid; triatomic.

tri-

prefix

1. three or thrice

   trigon

   triaxial

   trisect

2. occurring every three

   trimonthly

Word History and Origins

Origin of tri-¹

Middle English < Latin, combining form representing Latin trēs, tria, Greek treîs, tría three

Word History and Origins

Origin of tri-¹

from Latin trēs , Greek treis

Example Sentences

And also those that contain norgestimate, which include Ortho-Cyclen and Tri-Cyclen.

From The Daily Beast

It was the fall of 2012, and Hurricane Sandy had just devastated the Tri-State area.

From The Daily Beast

In a quote usually associated with Bill Stout, designer of the Ford Tri-Motor: “Simplicate and add more lightness.”

From The Daily Beast

Manhattan was the patient groom in my unspoken arranged marriage, the implicit goal of any tri-state suburban childhood.

From The Daily Beast

I remember Pham Thi Luyen who lived several provinces north in Trieu Ai village, Quang Tri Province.

From The Daily Beast

My weary shoulders fairly ache as we pass through the constant, or tri-yearly, recurrence of the same experience.

From Project Gutenberg

He rather prided himself on the way he played his part, and wore the tri-color cockade with an air of conviction.

From Project Gutenberg

Sabatier entered more carefully than he was wont to do, his hand upon a pistol thrust into his tri-color sash.

From Project Gutenberg

Tiny Moth planes stood wing to wing with huge tri-motored cabin ships that would hold a dozen passengers each.

From Project Gutenberg

Anthropolatry, an-thro-pol′a-tri, n. the giving of divine honours to a human being, a term always employed in reproach.

From Project Gutenberg

Words That Use Tri-

What does tri- mean?

Tri- is a combining form used like a prefix meaning “three.” Tri- is often used in a great variety of both everyday and technical terms.

Tri- ultimately comes from both Greek treîs, tría and Latin trēs, tria, all of which mean “three.”

Examples of tri-

An example of a word you may have encountered that features tri- is trident, “a three-pronged instrument or weapon.” The word trident comes from Latin tridēns, which uses the equivalent of the form tri- in the language.

The tri- part of the word means “three,” while the -dent part means “tooth.” Trident literally translates to “three teeth” or “three-toothed.”

Tri- also features in common words such as triangle and tricycle. Learn more about the origins of these words at their entries.

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

• triaxial
• tridimensional 
• tridymite (using the equivalent form of tri- in Greek)
• triethyl
• trifacial
• trifocal
• trifold
• trigram
• trihedral
• trihydrate
• trihydroxy

The following words use the equivalent forms of tri- in Latin or Greek:

• triad
• triarchy
• triceps
• tridactyl
• tridentate
• triduum
• triennial
• trifolium
• triform
• trigamy
• triglyph
• trigone
• trimeter
• triplex
• tripod
• tritoma

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

• tetr-
• tor-
• tricho-
• trinitro-
• tris-
• -trix
• twi-

Not every word that begins with the letters tri- is necessarily using the combining form tri- to denote “three.” Learn why triage literally means “sorting” at our entry for the word.

Break it down!

Tripods are stands used for holding cameras and telescopes in place. The combining form -pod refers to  “foot.” With this in mind, what does tripod literally mean?