sir S1 W3 /sə; strong sɜː $ sər strong sɜːr/ BrE AmE noun
[ Date: 1200-1300 ; Origin: ⇨ ↑ sire 1 ]
1 . spoken used when speaking to a man in order to be polite or show respect:
‘Report back to me in an hour, sergeant.’ ‘Yes, sir.’
Can I help you, sir?
Sir! You dropped your wallet.
⇨ ↑ madam (1), ↑ ma'am
2 . Dear Sir/Sirs used at the beginning of a formal letter to a man or to people you do not know
3 . Sir a title used before the first name of a ↑ knight or ↑ baronet :
Sir Paul McCartney
Sir Jasper
4 . British English spoken used by children at school when speaking to or talking about a male teacher:
Sir, I’ve forgotten my homework.
Look out – sir’s coming back!
⇨ ↑ miss 2 (4)
5 . no/yes sir! ( also no/yes siree! especially American English ) old-fashioned spoken used to emphasize a statement or an answer to a question:
I will not have that man in my home, no sir!