EnglishMain Dictionary
sir
Universal Words
noun
1 used as a polite way of addressing a man whose name you do not know, for example in a shop/store or restaurant, or to show respect:
Good morning, sir. Can I help you? * Are you ready to order, sir? * 'Report to me tomorrow, corporal!' 'Yes, sir!' * 'Thank you very much.' 'You're welcome, sir. Have a nice day.'
compareMA'AM
seealsoMADAM
2 (Dear Sir / Sirs) used at the beginning of a formal business letter when you do not know the name of the man or people that you are dealing with:
Dear Sir / Sirs * Dear Sir or Madam
3 (Sir) a title that is used before the first name of a man who has received one of the highest British honours (= a KNIGHT), or before the first name of a BARONET:
Sir Paul McCartney * Thank you, Sir Paul.
compareLADY
4 (BrE) used as a form of address by children in school to a male teacher:
Please, sir, can I open a window?
compareMISS
IDIOMS
no sir!