"What in the name of Merlin are you doing?" said Ron, watching her as though fearful for her sanity.

Harry Potter and the Order of the Phoenix

What does the sentence truly mean? Is "in the name of Merlin" an idiom? I get the meaning of "in the name of": as someone else’s official representative, but I am not sure about the meaning of the whole phrase.

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    Related question on ELU: What's the meaning of “in God's name”? Commented Feb 2, 2019 at 14:16
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    Note that in the Harry Potter series, Merlin seems to be used a lot by the Wizarding community where Muggle expressions would contain some sort of reference to God or Jesus: “in the name of Merlin”, “Merlin’s beard”, etc. Commented Feb 2, 2019 at 16:58
  • @FumbleFingers I'm wondering why it hasn't put: "in the God's name"?
    – dan
    Commented Feb 2, 2019 at 22:32
  • @dan: In monotheistic ("there is only one God"; Christiantity, Islam,...) contexts, the standard English reference is just God, with no article. But we do include the article with the Lord. Commented Feb 3, 2019 at 13:14
  • @dan It's deliberate. It's to give an everyday phrase a magical equivalent, making you feel like you're part of a different, but related world
    – Au101
    Commented Feb 3, 2019 at 16:22

1 Answer 1


The original phrase was "in the name of God". The idea was that the speaker must tell the truth. They must swear an oath.


Judge: Tell me, did you steal the bread?

Accused: In the name of God, I swear that I did not steal the bread.


Lord of the manor: In the name of God man, What are you doing at my door?

Interloper: My lord I am only a poor peasant, trying to beg a crumb. This I swear.


As Sarriesfan points out in a comment. "in the name of Merlin" is an invention of the author, J.K. Rowling. It is not an idiom. She uses the name of a famous wizard from folklore as a euphemism for 'God'.

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    it might be worth mentioning to avoid any confusion that "In the name of Merlin" is not a standard idiom, it's something made up by J.K. Rowling to fit the background of Harry Potter.
    – Sarriesfan
    Commented Feb 2, 2019 at 14:37
  • @Sarriesfan - Good point, I'll add that. Commented Feb 2, 2019 at 14:46
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    i don't think it's a euphemism. Well, maybe in-univerise it is. But the point is she's taken an everyday phrase and made a magical equivalent. it's more of a reference. As a reader, you're supposed to notice the parallel, it's one of the things that makes Harry Potter so enjoyable and imersive to me
    – Au101
    Commented Feb 3, 2019 at 0:28

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