sir

音标发音

sir的基本意思是“先生”,是對男士的一種尊稱,多用於長者、上級或服務業中對男顧客的稱呼。是可數名詞,常用於單數形式。sir不可同姓氏連用,但可用於名字之前或名字與姓之前。
sir通常用於正式書信的開頭,如Dear Sir或Sirs,首字母要大寫。
sir的另一意思是“爵士”。在英國的非正式口語中, sir還可作“某人的男教師”解。
在口語中,Yes, sir或No, sir可用於廻答女性的提問。
與sir相對應的隂性名詞是madam。

used as a formal and polite way of speaking to a man, especially one who you are providing a service to or who is in a position of authority

People sometimes say sir as a polite way of addressing a man whose name they do not know, or an older man. For example, a shop assistant might address a male customer as sir.
Sir is the title used in front of the name of a knight or baronet.
You use the expression Dear Sir at the beginning of a formal letter or a business letter when you are writing to a man.