10 letters · 18 points in Scrabble
noun the side of a right triangle opposite the right angle
originFrom 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”).
Etymology from Wiktionary, CC BY-SA 3.0