hypotenuse

The story

1. Ancient Greek · derived fromὑποτείνουσα πλευρά“side subtending [the right angle]”
2. Latin · derived fromhypotenusa
3. English todayhypotenuse

From Latin hypotenusa, from Ancient Greek ὑποτείνουσα πλευρά (hupoteínousa pleurá, “side subtending [the right angle]”), from ὑποτείνουσα (hupoteínousa, “stretching, extending, subtending”), active participle of ὑποτείνω (hupoteínō, “subtend, stretch under”).