Number & MeasureGreek → English
Hypotenuse
/haɪˈpɒtənjuːs/noun
The side opposite the right angle in a right-angled triangle, always the longest.
The Greek roots
ὑπό
hypó
under
τείνειν
teínein
to stretch
Literally: “stretching underneath”
The story of the word
Euclid never uses a single word for it. He writes the line subtending the right angle, ἡ ὑποτείνουσα, a participle meaning the one stretching under, and the participle eventually got promoted to a noun. Under makes sense from the angle's point of view: the side lies across from it, spanning the gap between its two arms. The same stretching verb gives tendon, tone and tension.
- How it travelled
- Ancient Greek → Latin → English
- First recorded
- 1570s
Same family
tendontonetensionhypothesis
In a sentence
Square the two short sides, add them, take the root, and you have the hypotenuse.