godan verb (-su), transitive verb
speak ill of; disparage; run down
Used for criticizing or belittling someone or something, often in a harsh or unfair way.
彼はいつも人の作品をけなしてばかりいる。
He's always running down other people's work.
そんなに自分をけなさないでください。
Please don't put yourself down so much.