形容心肠非常狠毒thoroughly vicious; lost all one's natural goodness

• 面对正在河中的救命恩人怎么能说出这般丧尽天良的恶语来。

  How could one say such vicious and horrible words to the life-saver still in the river?

• 因为丧尽天良的纳粹医生拿战俘充当试验中的“海豚”

  because a vicious Nazi doctor used POWs as "dolphins" in experiments