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

The research, led by first author Dr Minh Tri Luu and research team leader Dr Shelley Wickham, focuses on the creation of modular DNA origami "voxels" that can be assembled into complex three-dimensional structures.

From Science Daily

Since then, competitions such as the Tri and Four Nations have replaced genuine Test series with the Aussies.

From BBC

With the help of a mysterious glowing ball of energy named Tri, Zelda is gifted the ability to travel into these rifts and heal them.

From Los Angeles Times

El Tri has won fewer than half its games since Qatar, was eliminated in the first round of this summer’s Copa América and drew just 25,271 for last week’s Rose Bowl match against New Zealand, its smallest crowd for a U.S. friendly in nearly three years.

From Los Angeles Times

They’ll be together on the Mexican bench for the first time Saturday when El Tri faces New Zealand at the Rose Bowl.

From Los Angeles Times

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?