SIR

(MAN) [noun] [as form of address] [formal] - used as a formal and polite way of speaking to a man, esp. one whom you are providing with a service or who is in a position of authorityWhat would you like, sir?"Did you hear what I said?" "Yes, sir."Compare madam; miss.See study section: Titles and forms of address(formal) 'Dear Sir' is the usual way of beginning a formal letter to a man whose name you do not know. 'Dear Sirs' can be used when writing to a company.(formal) 'Dear Sir or Madam' is used when you do not know whether the person you are writing to is a man or a woman.(formal) Sir is sometimes used instead of the name of a male teacher.Please sir, I don't understand.(US informal) I'm not going to ride the subway, no sir (= certainly not)!