Definition of Godwin's law in US English:

Godwin's law

noun

humorous
  • The theory that as an online discussion progresses, it becomes inevitable that someone or something will eventually be compared to Adolf Hitler or the Nazis, regardless of the original topic.

    ‘correcting others' errors, especially online, can quickly lead to invocations of Godwin's law’
    • ‘At the risk of being accused under Godwin's Law, I agree.’
    • ‘On second thoughts, stuff Godwin's Law: I will mention the war because it is thunderously relevant.’
    • ‘Sadly, he breaks Godwin's Law near the end.’
    • ‘That has to be a record for the longest period of time before Godwin's Law kicks in.’
    • ‘I look forward to the discussion my choices provoke and the number of irate emails I get before Godwin's Law comes into play.’
    • ‘But someone really ought to have warned him about Godwin's Law.’
    • ‘But there seems to be something there that turns normally intelligent, open-minded people rabid, with Godwin's Law coming into play at about the third post.’
    • ‘How do we talk about these things without running afoul of Godwin's Law?’
    • ‘Yet more evidence that Godwin's Law extends well past the confines of the Internet.’
    • ‘Godwin's Law thus practically guarantees the existence of an upper bound on thread length in those groups.’
    • ‘Do I get an extra point for being the first to invoke Godwin's Law?’
    • ‘It used to be that any hope for a reasonable debate was ended the second anyone called someone else a "Nazi" (see Godwin's Law).’
    • ‘You know it's quite difficult to contain the impulse to break Godwin's Law when I read things like this.’
    • ‘The comments are your usual online argument that even borders on Godwin's Law.’
    • ‘Godwin's Law has been invoked (again).’
    • ‘It was Godwin's law in action.’
    • ‘If there were ever a perfect example of a blog post title that violates Godwin's law, I reckon this is it.’
    • ‘Isn't that the lawyer's equivalent of Godwin's Law?’
    • ‘But I think I've already violated Godwin's Law enough for one week.’
    • ‘We're about a heart-beat from Godwin's Law, here.’

Origin

1990s: named after Mike Godwin (b.1956), the US lawyer and author who originated the theory.