9 letters · 16 points in Scrabble
noun a soft silvery metallic element; a rare earth of the lanthanide series; it occurs in gadolinite and monazite and xenotime
originFrom Ytterby + -ium, named after Ytterby, Sweden, the same etymological source as yttrium, terbium, and erbium.
Etymology from Wiktionary, CC BY-SA 3.0