13 letters · 26 points in Scrabble
adjective not capable of being conquered or vanquished or overcome; - R.E.Danielson
adjective incapable of being surmounted or excelled
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 conquerable English unconquerable From un- + conquerable.
Etymology from Wiktionary, CC BY-SA 3.0