To despise, scorn, or look down on someone; to treat someone as of little worth, often with contempt.
彼女は努力を認めず、他人を蔑むような言い方をした。
She refused to acknowledge the effort and spoke in a way that looked down on others.
どんな立場の人でも蔑んではいけない。
You must not scorn people regardless of their position.
彼は弱い者を蔑む癖があると評判だ。
He's reputed to have a habit of looking down on the weak.