What does trapezoid mean?
Trapezoid is a noun naming a type of quadrilateral, but its precise meaning depends strongly on regional convention. In modern American mathematics, it usually means a quadrilateral with at least one pair of parallel sides, so a parallelogram also meets the inclusive definition. British English instead uses trapezoid for a quadrilateral with no parallel sides and trapezium for one with a single pair. Some older American definitions also exclude parallelograms by requiring that a trapezoid have no parallel sides. Outside mathematics, the term appears in architecture, graphic design, anatomy, and technical writing for shapes or structures resembling the relevant geometric form. Familiar examples include an isosceles trapezoid, the trapezoid rule in calculus, the trapezoid muscle, and the trapezoid bone of the wrist. Although the word has no close synonym that resolves the regional distinction, understanding the British-American difference is essential in technical and educational contexts.
nounA quadrilateral with at least one pair of parallel sides in modern American mathematical usage, though traditional American definitions restrict the term to quadrilaterals with no parallel sides. In British English, a trapezoid is a quadrilateral with no parallel sides.
- In modern American mathematical usage, a quadrilateral with at least one pair of parallel sides, including parallelograms under the inclusive definition.
- In British English, and in some traditional American definitions, a quadrilateral with no parallel sides.
- An anatomical structure with a roughly trapezoidal shape, such as the trapezoid muscle or trapezoid bone.
"The architect designed the window as a broad trapezoid, with two long sides parallel to the ceiling and floor."
"The designer placed a blue trapezoid at the center of the logo."
"Her doctor explained that the X-ray showed a fracture in a trapezoid bone in her wrist."
The regular plural is used for geometric shapes and for anatomical structures called trapezoids.
"The drawing contains two trapezoids of different sizes."
A shape whose name depends on which side of the Atlantic you are standing on.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does trapezoid come from?
The word entered English through Latin from Greek, where the family of terms was based on trapeza, meaning “table.” The Greek forms referred to a shape resembling a table or trapezium. Trapezoid, trapezium, trapeze, and related words such as trapezist share this table-shaped etymological origin.
Related word forms
How trapezoid is actually used
The word is chiefly used in mathematics, architecture, design, and anatomy. Its definition varies significantly between British and American English, and older mathematical texts may use the exclusive definition even in American contexts.
Easily confused with trapezoid
In British English, a trapezium has at least one pair of parallel sides and a trapezoid has none; in American English, that naming is typically reversed.