trapezoid

American  

[trap-uh-zoid] / ˈtræp əˌzɔɪd /

noun

1. Geometry.

   1. a quadrilateral plane figure having two parallel and two nonparallel sides.

   2. British. trapezium.

2. Anatomy. a bone in the wrist that articulates with the metacarpal bone of the forefinger.

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adjective

1. Geometry. Also trapezoidal. of, relating to, or having the form of a trapezoid.

trapezoid British  

/ ˈtræpɪˌzɔɪd /

noun

1. a quadrilateral having neither pair of sides parallel

2. Also called: trapezium.  a quadrilateral having two parallel sides of unequal length

3. a small bone of the wrist near the base of the index finger

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trapezoid Scientific  

/ trăp′ĭ-zoid′ /

1. A four-sided plane figure having two parallel sides.

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trapezoid Cultural  

1. A four-sided polygon in which two sides are parallel and two are not.

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Other Word Forms

• posttrapezoid adjective
• subtrapezoid adjective
• subtrapezoidal adjective

Etymology

Origin of trapezoid

First recorded in 1695–1705; from New Latin trapezoīdēs, from Late Greek trapezoeidḗs “trapezium-like”; trapezium, -oid

Explanation

In geometry a trapezoid is a four-sided figure with two sides that are parallel. Imagine taking an equilateral triangle and chopping its tip off so that it's made up of two parallel lines on top and bottom and you've got a trapezoid. The word trapezoid comes from the Greek trapeza meaning "table" and -oeides meaning "shaped." Think of a trapezoid as table-shaped. It has a pair of parallel sides that are also known as the bases of the figure. To find the area of a trapezoid, take the average of the bases and multiply it by the height. In anatomy, the trapezoid is the smallest of the eight small bones in the wrist.

Example Sentences

On a concrete plateau on a mountain overlooking the ice-dotted fjord sits the base’s radar building, a massive brutalist structure shaped like a concrete-and-steel trapezoid.

From The Wall Street Journal • Oct. 12, 2025

I was hoping Joe would feel some similarly competitive outrage toward the rolling trapezoid, deficient in Americana, ignorant of history, nothing like the estimable Hummer.

From Slate • Jun. 22, 2025

Zach Hyman took a cross-checking minor and Skinner was penalized for playing the puck outside the trapezoid.

From Seattle Times • May 11, 2023

He’s a trapezoid peg in the square hole of signal callers.

From Washington Post • Jul. 15, 2022

Egypt is a yellow trapezoid with one right angle, and looks like the cornerstone of a pyramid.

From "Dry" by Neal Shusterman and Jarrod Shusterman