tri-

American  

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

   triacid; triatomic.

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tri- British  

prefix

1. three or thrice

   triaxial

   trigon

   trisect

2. occurring every three

   trimonthly

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Usage

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.”

Etymology

Origin of tri-

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

Example Sentences

If you have access to pliable pruned fruit tree branches, you can make tri- or quad-podded structures for your summer crops.

From New York Times • Jun. 19, 2013

Among them are the corn-fed chicken itself; modified cornstarch; mono-, tri-, and diglycerides; dextrose; lecithin; yellow corn flour; regular cornstarch; vegetable shortening; partially hydrogenated corn oil.

From "The Omnivore's Dilemma" by Michael Pollan

Foliolate, having leaflets; the number indicated by the Latin prefixes, bi-, tri-, etc.

From The Wild Flowers of California: Their Names, Haunts, and Habits by Parsons, Mary Elizabeth

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 is equivalent to a gain in weight of 44 per cent. for the tri- nitrate, and 58 per cent. for the tetra-nitrate.

From Nitro-Explosives: A Practical Treatise by Sanford, P. Gerald (Percy Gerald)