13 letters · 17 points in Scrabble
adjective not to be exceeded
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 surpassable English unsurpassable From un- + surpassable.
Etymology from Wiktionary, CC BY-SA 3.0