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• sir
  sir

  noun

  a respectful or formal term of address used to a man.
• Sir
  Sir

  noun

  a title of honour placed before the name of a knight or baronet

sir

American  

[sur] / sɜr /

noun

1. a respectful or formal term of address used to a man.

   No, sir.

2. (initial capital letter) the distinctive title of a knight or baronet.

   Sir Walter Scott.

3. (initial capital letter) a title of respect for some notable personage of ancient times.

   Sir Pandarus of Troy.

4. a lord or gentleman.

   noble sirs and ladies.

5. an ironic or humorous title of respect.

   sir critic.

6. Archaic. a title of respect used before a noun to designate profession, rank, etc..

   sir priest; sir clerk.

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Sir ¹ British  

/ sɜː /

noun

1. a title of honour placed before the name of a knight or baronet

   Sir Walter Raleigh

2. archaic a title placed before the name of a figure from ancient history

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sir ² British  

/ sɜː /

noun

1. a formal or polite term of address for a man

2. archaic a gentleman of high social status

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Usage

What is a basic definition of sir? Sir is a respectful form of address for a man or a term for a gentleman. When capitalized, Sir is used as a title for a knight. The word sir has a few other senses as a noun. Sir is a respectful term used to address a man. Sir is especially likely to be used to refer to a person of higher rank or authority. In this sense, sir is the male equivalent of madam or ma’am.

• Real-life examples: Waiters or other service workers are very likely to use sir when addressing male customers. Members of the military will refer to superior officers as sir or ma’am when not using their title or rank. A person may refer to their boss or manager as sir.
• Used in a sentence: The recruits answered the drill sergeant with a loud “Sir, yes, sir!”

Sir can also be used to refer to a gentleman or a lord, especially in a formal setting.

• Used in a sentence: I meant no offense to the good sir or his noble family.

The capitalized Sir indicates that a man is a knight or a baronet.

• Real-life examples: Sir Lancelot and Sir Gawain were two of the knights who served the legendary King Arthur. Sir Isaac Newton and Sir Walter Raleigh are famous historical figures who were knighted. Sir Sean Connery, Sir Patrick Stewart, and Sir Ian McKellan are three modern actors who were knighted by Queen Elizabeth II.
• Used in a sentence: Because Gregory had served Great Britain loyally for over 50 years, he was knighted and became Sir Gregory.

Etymology

Origin of sir

1250–1300; Middle English; unstressed variant of sire

Explanation

Use the word sir as a formal title for a man. People often use sir to respectfully or politely address someone they don't know well. When you're saying hello to a man who's been knighted by the Queen of England, you should call him sir — it's the official way to address a knight. You can also use this word when you're writing a formal business letter: "Dear Sir or Madam, I am interested in applying for a job at your candy company." And if you're a waiter, you might use it too: "Your hamburger, sir."

Example Sentences

Many people are admirers of Sir David Attenborough's work and his devotion to animals throughout his life.

From BBC • May 7, 2026

Wanting only the best for Sir David, the duo "disappeared into her room" and used some of her finest pens to make the drawing extra special.

From BBC • May 7, 2026

Despite the 94-year age gap between the two, Max described Sir David as his "favourite person" and said he feels happy for him to reach such a milestone.

From BBC • May 7, 2026

In a letter sent to government employees across Whitehall on Wednesday afternoon, Sir Keir told them he recognised "the events of the last recent weeks have felt unsettling".

From BBC • May 6, 2026

Suddenly Sir Fig Newton jumped up onto all fours, his claws digging through my shirt and clamping into my skin.

From "Sir Fig Newton and the Science of Persistence" by Sonja Thomas

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