# diagonal

## Definitions

### General English

### General Science

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

### Aviation

- noun a
__line__joining two opposite corners of a rectangle

### 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*.