11 letters · 13 points in Scrabble
originLearned borrowing from French inénarrable, from Latin inēnārrābilis (“indescribable”), from in- (prefix meaning ‘not’) + ēnārrābilis (“describable, explainable”). Ēnārrābilis is derived from ēnārrāre + -bilis (suffix forming adjectives indicating a capacity or worth of being acted upon); ēnārrāre is the present active infinitive of ēnārrō (“to explain in detail, expound”), from ē- (a variant of…
Etymology from Wiktionary, CC BY-SA 3.0