Number & MeasureGreek → English
Diagonal
/daɪˈæɡənəl/adjective
Running from one corner of a figure to a non-adjacent corner, or slanting across.
The Greek roots
διά
diá
through, across
γωνία
gōnía
angle, corner
Literally: “through the angles”
The story of the word
Euclid speaks of the line δια γωνίας, from angle to angle, and the word describes exactly that path rather than a vague slant. The everyday sense of a tilted stripe came much later, once the geometry term escaped the textbook. The second root also sits inside polygon, pentagon and trigonometry.
- How it travelled
- Ancient Greek → Latin → Middle French → English
- First recorded
- 16th century
The same roots elsewhere
Other languages reached for exactly the same Greek pieces.
Same family
polygonpentagontrigonometryorthogonal
In a sentence
He crossed the square on the diagonal to save half a minute.