Letters and spelling

Words that start with tri

Tri- is a prefix meaning three, and it appears across math, sports, and everyday nouns. This list helps students spot the pattern in words like triangle and tricycle, practice spelling words that share the same beginning, and see how one small prefix can carry a consistent meaning across many words.

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Words that start with tri

Word	Meaning	In a sentence
trianglenoun	A geometric shape with three straight sides and three angles.	The teacher drew a triangle on the board to explain its three angles.
tricyclenoun	A small, pedal-powered vehicle with three wheels, often ridden by young children.	The toddler pedaled her red tricycle happily around the driveway all afternoon.
tripodnoun	A three-legged stand used to support and steady a camera, telescope, or similar device.	She mounted the camera on a tripod to keep the long exposure shot steady.
trionoun	A group of three people, especially musicians, performing or acting together.	The jazz trio played a slow, moody number to close the evening.
tripleverb	To make something three times as large or numerous, or a thing consisting of three parts.	The company tripled its profits after expanding into international markets.
triathlonnoun	An athletic race combining swimming, cycling, and running, completed consecutively by each competitor.	She trained for months to complete her first triathlon without stopping.
tridentnoun	A spear with three prongs, traditionally carried by sea gods such as Poseidon and Neptune.	The statue in the fountain shows Neptune raising his trident above the waves.
triceratopsnoun	A large plant-eating dinosaur with three horns on its face and a bony neck frill.	The museum's new exhibit featured a full skeleton of a triceratops.
trilogynoun	A group of three related novels, films, or other works that form a single larger story.	The director's fantasy trilogy took nearly a decade to complete.
tripletnoun	One of three children born at the same birth, or any group of three similar things.	The triplets each had a distinct personality despite looking almost identical.
trivianoun	Small, unimportant facts or details, often used as the basis of a quiz game.	He impressed his friends with obscure trivia about classic films.
triagenoun	The process of sorting people or cases by urgency to decide the order they are treated.	Nurses performed triage in the emergency room to treat the most critical patients first.
tribunalnoun	A panel or court set up to make judgments on specific disputes or legal matters.	The employment tribunal ruled that the company had dismissed her unfairly.
triumphnoun	A great victory or success, often achieved after a difficult struggle.	Winning the championship was a triumph for a team that lost every game last year.
trinitynoun	A group of three closely connected people, elements, or things considered as one unit.	Speed, agility, and strength form the trinity of skills every sprinter needs.
trifectanoun	A combination of three related, especially favorable, events, wins, or qualities occurring together.	Winning the award, the promotion, and the new house was quite a trifecta for her.
trimesternoun	A period of about three months, especially one of three divisions of pregnancy or an academic year.	Doctors monitor different developments in each trimester of a pregnancy.
triangularadjective	Having the shape of a triangle, or involving three parts, sides, or parties.	The roof had a triangular window that let in the morning light.
trilingualadjective	Able to speak or write three languages fluently, or conducted in three languages.	Growing up in Switzerland, she became trilingual in French, German, and Italian.
tripartiteadjective	Consisting of, involving, or divided into three parts or parties.	The tripartite agreement bound the government, the union, and the employers.
trisectverb	To divide something into three parts, typically of equal size.	The geometry problem asked students to trisect the given angle using only a compass.
triweeklyadjective	Occurring three times a week, or, less commonly, once every three weeks.	The gym offers a triweekly yoga class on Monday, Wednesday, and Friday.
triannualadjective	Occurring three times each year, typically spaced about four months apart from one another.	The company holds a triannual meeting to review its budget each spring, summer, and fall.
tricoloradjective	Having three colors, especially arranged in bands, as on certain national flags.	The French flag is a well-known tricolor of blue, white, and red.
tricepnoun	The large muscle along the back of the upper arm that straightens the elbow.	He did dips at the gym to build up his triceps.
triplexnoun	A building divided into three separate living units, or an apartment on three levels.	They bought a triplex and rented out the other two units for income.
tripwirenoun	A thin wire stretched close to the ground that triggers a trap or alarm when disturbed.	The soldiers spotted a tripwire connected to an explosive hidden in the brush.
trivialadjective	Of little value or importance; not worth serious attention.	They argued for an hour over a trivial detail in the seating chart.

Frequently asked questions

What does the prefix tri- mean?

Tri- comes from Latin and Greek and means three, as seen in words like triangle, tricycle, and triathlon.