8 letters · 10 points in Scrabble
noun a toxic nonmetallic element related to sulfur and tellurium; occurs in several allotropic forms; a stable grey metallike allotrope conducts electricity better in the light than in the dark and is used
originFrom French sélénium, the name coined by Swedish chemist Jöns Jacob Berzelius in 1818 from Ancient Greek σελήνη (selḗnē, “moon”) in reference to original confusion with the similar element tellurium.
Etymology from Wiktionary, CC BY-SA 3.0