卑怯

ここで逃げ出すのは卑怯だ。

It would be cowardly to run away now.

責任から逃げるような卑怯な真似はしたくない。

I don't want to do anything as cowardly as running from my responsibilities.

面と向かって言えないなんて卑怯者だ。

Not being able to say it to my face makes him a coward.

後ろから攻撃するなんて卑怯だぞ。

Attacking from behind is a dirty trick!

彼は試合に勝つために卑怯な手を使った。

He used underhanded tactics to win the match.

弱みにつけ込むのは卑怯なやり方だ。

Taking advantage of someone's weakness is an unfair way to do things.