sir
//sɜː(r)//
Noun
1
A polite or formal term of address for a man, especially one in a position of authority or to whom respect is shown
Excuse me, sir. Can you help me?
2
Used as a title before the first name of a knight or baronet
Sir Paul McCartney was knighted in 1997.
3
Used at the beginning of a formal letter to a man whose name is unknown
Dear Sir, I am writing to inquire about your services.
Verb
1
To address someone as 'sir'
Don't sir me, we're friends.