also: ぐにん
noun
A somewhat literary or formal term for a foolish person; less common in casual speech than 馬鹿 (ばか) or 阿呆 (あほう).
彼は自分の過ちに気づかない愚人だ。
He is a fool who doesn't realize his own mistakes.
愚人も時には賢いことを言う。
Even a fool sometimes says something wise.
Compound of 愚 (ぐ, foolish) and 人 (じん, person). The reading ぐにん uses the older go-on reading for 人.