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trigonometry

American  
[trig-uh-nom-i-tree] / ˌtrɪg əˈnɒm ɪ tri /

noun

  1. the branch of mathematics that deals with the relations between the sides and angles of plane or spherical triangles, and the calculations based on them.

trigonometry British  
/ ˌtrɪɡəˈnɒmɪtrɪ, ˌtrɪɡənəˈmɛtrɪk /

noun

  1.  trig.  the branch of mathematics concerned with the properties of trigonometric functions and their application to the determination of the angles and sides of triangles. Used in surveying, navigation, etc

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
trigonometry Scientific  
/ trĭg′ə-nŏm′ĭ-trē /

  1. The study of the properties and uses of trigonometric functions.

Other Word Forms

  • nontrigonometric adjective
  • nontrigonometrical adjective
  • nontrigonometrically adverb
  • trigonometric adjective
  • trigonometrical adjective
  • trigonometrically adverb
  • untrigonometric adjective
  • untrigonometrical adjective
  • untrigonometrically adverb

Etymology

Origin of trigonometry

1605–15; < New Latin trigōnometria; trigon, -o-, -metry

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

In the years following graduation, Jenner and Pratt would team up to produce “The Princes Of Malibu,” but only after Pratt, who was attending USC, almost flunked a course in business trigonometry.

From Los Angeles Times • Jan. 27, 2026

One dude jokes, “If only I remembered any trigonometry, this would be easy.”

From Slate • Jul. 7, 2025

You know what's more difficult than advanced trigonometry?

From Salon • Apr. 9, 2024

"I have lost count of the number of people who say they wish they had learnt about mortgages rather than trigonometry," she said.

From BBC • Apr. 19, 2023

So he purchased a book on trigonometry but soon found himself unable to follow the geometrical arguments.

From "Cosmos" by Carl Sagan

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.