13 letters · 20 points in Scrabble
adjective not grammatical; not conforming to the rules of grammar or accepted usage
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 grammatical English ungrammatical From un- + grammatical.
Etymology from Wiktionary, CC BY-SA 3.0