sir

sir [ weak sər, strong sɜr ] *

1. ) SPOKEN used as a polite way of speaking to a man. This word can be used by someone who works in a store or restaurant for speaking to a customer, by someone speaking to a senior officer, or by someone speaking to another person whose name they do not know:

That'll be $5.50, please, sir.

Would you like a drink, sir?

Excuse me sir, do you know what the time is?

a ) AMERICAN used by a boy or young man as a polite way of speaking to an older man:

Does your mother know about this? No, sir.

2. ) BRITISH SPOKEN used by students for talking to or about a male teacher:

If you don't know the answer, ask sir.

Sir, may I go to the toilet?

3. ) Sir used before the name of a man who is a KNIGHT or BARONET

Dear Sir

used for beginning a letter to a man whose name you do not know

yes/no sir AMERICAN INFORMAL OLD-FASHIONED

used for emphasizing what you are saying:

Yes sir, we're really rolling now.