“When Pigs Fly” is a humorous idiom expressing disbelief that an event will ever happen. Oxford distinguishes the North American form from British “pigs might fly”; no exact first-use claim is made here.
ReviewedEvidence1 sourceSectionPhrases & Idioms
Quick answer
“When pigs fly” is a humorous way to say you believe something will never happen.
Key details
Canonical Formwhen pigs fly
Core Meaningused to show disbelief that something will ever happen
Further guidance
History Boundary
The documented modern meaning is published without claiming an exact inventor, coinage date, or absolute first use.
Meaning
used to show disbelief that something will ever happen
Usage Boundary
Use it to express strong disbelief or impossibility, not an ordinary low-probability forecast.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
“A blessing in disguise” describes something that initially seems bad or unlucky but later produces a good result. Specialist history places the printed phrase in the mid-eighteenth century, while earlier texts may express similar ideas without proving the same idiom.
The informal idiom “not have a snowball’s chance in hell” describes a situation with essentially no chance of success. This guide limits the page to the current form, register, and meaning supported by Cambridge and does not add an unsupported origin story.
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Alternative Trading System is a current federal securities-regulation defined term. This guide preserves the rule-specific definition and boundaries instead of replacing it with informal market shorthand.
