flippant

1. ADJ If you describe a person or what they say as flippant, you are criticizing them because you think they are not taking something as seriously as they should. 轻率的[表不满]

Don't be flippant, damn it! This is serious!

该死，不要不当回事！这是很严肃的！

He now dismisses that as a flippant comment. 他现在把那当作一个轻率的评论，不再理会了。