sir

UK: 'sir', 'Sir': /ˈsɜː/ US: /sɝ/ ,(sûr)

WordReference Random House Learner's Dictionary of American English © 2025

sir /sɜr/   n. [countable]

1. • a formal term of address used to a man:
     "Dear Sir,'' the letter began.
2. the title of a knight or baronet:
   [Sir] Sir Walter Scott.
3. a lord or gentleman:
   noble sirs and ladies.

See -sene-.

WordReference Random House Unabridged Dictionary of American English © 2025

sir  (sûr), n. 

1. a respectful or formal term of address used to a man:
   No, sir.
2. (cap.) the distinctive title of a knight or baronet:
   Sir Walter Scott.
3. (cap.) 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.

• 1250–1300; Middle English; unstressed variant of sire

Collins Concise English Dictionary © HarperCollins Publishers::

sir / sɜː/ noun

1. a formal or polite term of address for a man
2. a gentleman of high social status

Etymology: 13th Century: variant of sire

Collins Concise English Dictionary © HarperCollins Publishers::

Sir / sɜː/ noun

1. a title of honour placed before the name of a knight or baronet: Sir Walter Raleigh
2. a title placed before the name of a figure from ancient history