The word 'lout' often implies disapproval and is used to express a strong negative opinion about someone's behavior. His loud outburst at dinner showed him to be a complete lout.
Pro Tip 2/3
Gender Specific
While 'lout' typically refers to men, it can be used for any gender when stressing clumsy rudeness. She behaved like a lout when she mocked the performers.
Pro Tip 3/3
Casual Context
Use 'lout' in casual or informal contexts; it might not be suitable for formal writing or speech. At the pub, a lout spilled his drink all over me.