# diagonal

## Definitions

### General English

### General Science

- adjective referring to a line,
__plane__or structure that slopes halfway between the vertical and horizontal

### Aviation

### Construction

- A straight
__structural____member____forming__the__hypotenuse__of a right triangle, as in the diagonal bracing of a stud__wall__.

### Economics

- In a matrix, the elements on a straight line from the top left to the bottom right, or occasionally from the bottom left to the top right.
- In an Edgeworth box, the straight line from the bottom left corner to the top right. Along the diagonal, the ratios of allocations of the two agents (industries or consumers) are constant and equal.
- In an integrated
__world economy__diagram, the straight line from the bottom left corner to the top right. Along the diagonal, the ratios of__factor__endowments of the two coutries are constant and equal.

## Origin & History of “diagonal”

*Diagonal*is commonly used simply as a synonym for

*oblique*, but in

__strict__mathematical terms it denotes a line joining two non-adjacent angles of a polygon.

__this__reveals far

__more__clearly its origins. It comes from

*diagōnālis*, a Latin adjective derived from Greek

*diagṓnios*. This was a compound formed from the prefix

*dia*- ‘across’ and

*gōníā*‘angle’ (as in

__English__

*polygon*), meaning ‘from

__angle__to angle’.

*Gōníā*is related ultimately to English

*knee*and

*genuine*.