Number & MeasureGreek → English
Diameter
/daɪˈæmɪtər/noun
A straight line passing through the centre of a circle from one side to the other.
The Greek roots
διά
diá
through, across
μέτρον
métron
measure
Literally: “measure across”
The story of the word
διάμετρος is the measure taken across, and Greek geometers used the same word for the diagonal of a rectangle, which is the same idea applied to corners. Euclid defines it as the straight line through the centre cut off both ways by the circumference, and that is still the definition in every textbook. English took the word, and the geometry with it, in the late fourteenth century.
- How it travelled
- Ancient Greek → Latin → Old French → English
- First recorded
- 14th century
The same roots elsewhere
Other languages reached for exactly the same Greek pieces.
Same family
perimetermetregeometrysymmetry
In a sentence
Measure the diameter at the widest point or the lid will not seat.