This is pejorative term. It is used to describe a person who feels or acts as if they are morally superior to other people. For example, if someone says they believe people should never drink alcohol or get drunk, you might say "don't be so self righteous" . In other words, don't be intolerant about other people's weaknesses and try and pretend you are better than them. "Your'e being very self-righteous about drinking now. When you were a student you used to have a beer in your hand permanently!"

Hi Eric, A "self-righteous" person is someone who always thinks they are morally right, morally superior etc. It is usually used in a negative sense.

自以为是的

金山词霸解释“自以为是”，我看了英文解释和另两位评论者的解释，觉得翻成“道貌岸然”比较合适。