10 letters · 13 points in Scrabble
adjective free from admixture with noxious elements; clean
originEtymology tree Proto-Indo-European *né Proto-Indo-European *n̥- Proto-Germanic *un- Proto-West Germanic *un- Old English un- Middle English un- English un- English polluted English unpolluted From un- + polluted.
Etymology from Wiktionary, CC BY-SA 3.0