# principal diagonal

- Mathematics. See under diagonal(def 9).

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## Origin of principal diagonal^{}

First recorded in 1960–65

# diagonal

[dahy-ag-uh-nl, -ag-nl]

- Mathematics.
- connecting two nonadjacent angles or vertices of a polygon or polyhedron, as a straight line.
- extending from one edge of a solid figure to an opposite edge, as a plane.

- having an oblique direction.
- having oblique lines, ridges, markings, etc.

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- a diagonal line or plane.
- virgule.
- a diagonal row, part, pattern, etc.
- Manège. (of a horse at a trot) the foreleg and the hind leg, diagonally opposite, which move forward simultaneously.
- diagonal cloth.
- Mathematics. a set of entries in a square matrix running either from upper left to lower right (main diagonal or principal diagonal) or lower left to upper right (secondary diagonal).
- Chess. one of the oblique lines of squares on a chessboard: He advanced his bishop along the open diagonal.

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## Origin of diagonal^{}

Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

# diagonal

- maths connecting any two vertices that in a polygon are not adjacent and in a polyhedron are not in the same face
- slanting; oblique
- marked with slanting lines or patterns

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- maths a diagonal line or plane
- chess any oblique row of squares of the same colour
- cloth marked or woven with slanting lines or patterns
- something put, set, or drawn obliquely
- another name for solidus (def. 1)
- one front leg and the hind leg on the opposite side of a horse, which are on the ground together when the horse is trotting

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## Word Origin

C16: from Latin diagōnālis, from Greek diagōnios, from dia- + gōnia angle

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

## Word Origin and History for principal diagonal

# diagonal

Online Etymology Dictionary, © 2010 Douglas Harper

# diagonal

[dī-ăg′ə-nəl]

- Connecting two nonadjacent corners in a polygon or two nonadjacent corners in a polyhedron that do not lie in the same face.

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- A diagonal line segment.

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The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.