I. dī-ˈa-gə-n ə l, -ˈag-nəl adjective
Etymology: Latin diagonalis, from Greek diagōnios from angle to angle, from dia- + gōnia angle; akin to Greek gony knee — more at knee
Date: 1563
1.
a. : joining two vertices of a rectilinear figure that are nonadjacent or two vertices of a polyhedral figure that are not in the same face
b. : passing through two nonadjacent edges of a polyhedron
a diagonal plane
2.
a. : inclined obliquely from a reference line (as the vertical)
wood with a diagonal grain
b. : having diagonal markings or parts
a diagonal weave
II. noun
Date: 1571
1. : a diagonal straight line or plane
2.
a.
(1) : a diagonal direction
(2) : a diagonal row, arrangement, or pattern
b. : something oriented in diagonal position
3. : slash 4
•
- on the diagonal