12 letters · 17 points in Scrabble
adjective not open to question; obviously true
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- Latin disputo Proto-Indo-European *-dʰlom Proto-Indo-European *-dʰlis Proto-Italic *-ðlis Latin -bilis Latin disputābilislbor. English disputable English undisputable From un- + disputable.
Etymology from Wiktionary, CC BY-SA 3.0