na-adjective, noun
nonsensical; absurd; incoherent; irrelevant
Describes statements, answers, or behavior that are logically inconsistent, off the mark, or make no sense. Often used in casual conversation.
His explanation was nonsensical, and I had no idea what he was trying to say.
質問に対してとんちんかんな答えが返ってきた。
I got an irrelevant answer to my question.