Bedeutung von “sir” im Essential American English Dictionary

sir

noun us /sɜr/

B1 You call a man “sir” when you are speaking to him politely:

Excuse me, sir, is this seat taken?
Dear Sir

a way of beginning a formal letter to a man whose name you do not know

Sir

a title used in the UK before the name of a man who has been given official respect or who has a high social rank:

Sir Cliff Richard

(Definition von “sir” aus dem Webster's Essential Mini Dictionary © Cambridge University Press)