Focus on the pronunciation of Sir
English definition of “Sir”
/sɜːr/ noun [S] formal
› a formal and polite way of speaking to a man: May I help you, Sir?
Dear Sir › the usual way of beginning a formal letter to a man whose name you do not know: Dear Sir, I am writing to complain about the quality of the service I received last week.
Dear Sir or Madam › used to begin a formal letter when you do not know whether the person you are writing to is a man or a woman: Dear Sir or Madam, I am writing to inform you that I wish to cancel my credit card.
Dear Sirs old-fashioned › used to begin a letter to a company when you do not have someone's name to write to directly → Compare Madam