When Pigs Fly (Origin)

What Is the Origin of the Saying "When Pigs Fly"?

The term "when pigs fly" means something that will never ever happen.

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When Pigs Fly (Origin)

Examples of Use:

  • Why did you lend her £100? You'll get that back when pigs fly!
  • I'll join the chess club when pigs fly.
  • He said he'll clean his house. If he actually does it, pigs may fly.
The idiom "when pigs fly" (or "pigs might fly," "pigs may fly") is an example of an adynaton, which is a figure of speech in the form of hyperbole (exaggeration) to such an extent as to imply impossibility. Here are some other common examples of adynaton:
  • To make a mountain out of a molehill
  • To pass a camel through the eye of a needle
  • When hell freezes over
  • Hen's teeth
  • Wenn Ostern und Weihnachten zusammenfallen
  • (German for "When Easter and Christmas coincide")
Similar expressions feature in other languages:
  • "kun lehmat lentavat" – when cows fly (Finnish)
  • "Cuando las vacas vuelen" – when cows fly (Spanish)
  • "Quando gli asini voleranno" – when donkeys fly (Italian)
The original version of "pigs might fly" was "pigs fly with their tails forward." This version featured in John Withals' 1616 "A Shorte Dictionarie for Yonge Begynners" (an English-Latin dictionary). Withal's entry reads:
  • "Pigs fly in the ayre with their tayles forward.
The expression was used as a sarcastic rebuttal to an overly optimistic prediction. It is used in the same way today but in a shorter form. For example:
  • I think Jane will say yes if I ask her to the dance.
  • Yeah, when pigs fly.
  • ("When pigs fly" is the preferred version in the US. In the UK, "pigs might/may fly" is more common.)

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This page was written by Craig Shrives.