Etymology
Advertisement

diagonal (adj.)

early 15c. (implied in diagonally), "extending as a line from one angle to another not adjacent," from Old French diagonal, from Latin diagonalis, from diagonus "slanting line," from Greek diagonios "from angle to angle," from dia "across, through" (see dia-) + gōnia "angle, corner" (from PIE root *genu- (1) "knee; angle").

As a noun, from 1570s, "straight line drawn from one angle to or through another not adjacent, in a plane or solid figure." In chess, "a line of squares running diagonally across a board."

Others are reading

Advertisement
Advertisement
Definitions of diagonal
1
diagonal (n.)
(geometry) a straight line connecting any two vertices of a polygon that are not adjacent;
diagonal (n.)
a line or cut across a fabric that is not at right angles to a side of the fabric;
Synonyms: bias
diagonal (n.)
an oblique line of squares of the same color on a checkerboard;
the bishop moves on the diagonals
diagonal (n.)
(mathematics) a set of entries in a square matrix running diagonally either from the upper left to lower right entry or running from the upper right to lower left entry;
diagonal (n.)
a punctuation mark (/) used to separate related items of information;
2
diagonal (adj.)
connecting two nonadjacent corners of a plane figure or any two corners of a solid that are not in the same face;
a diagonal line across the page
diagonal (adj.)
having an oblique or slanted direction;
Synonyms: aslant / aslope / slanted / slanting / sloped / sloping
From wordnet.princeton.edu