at the expense of so or sth meaning

• [American slang]
  Fig. to the detriment of someone or something; to the harm of someone or something.
    He had a good laugh at the expense of his brother.
    He took a job in a better place at the expense of a larger income.

• at the expense of:    1. To the cost or ...
• be at the expense of:    To pay the cost of
• expense:    Noun: expense  ...