Sir - sire

Sir is a more modern form of the older sire. (The form sire was more strongly stressed in the past. So, as the honorific became less stressed, the vowel was reduced from the diphthongal /aɪ/ to the usual English unstressed form short vowel /ə/, the shwa.) The origin of the word lies in an aphetic form of the Latin senior, 'older', 'more worthy of respect'.

• Sire is now obsolete, except in
  • the highly formal situation of addressing a king;
  • historical fiction and other circumstances where a writer is deliberately using its obsolescence;
  • as a verb meaning 'to father', particularly of pedigree animals used for breeding such as (particularly) racehorses. In Early Modern English, it was regularly used for humans: Shakespeare wrote in Cymbeline (1623) "Cowards father Cowards, and base things sire base" (IV ii 26). Consequently it is still used as a noun meaning 'father': though this is now not common literally, it may still be used to indicate 'inventor', 'founder' or 'originator' - of an idea, a process, a school of criticism etc.