Of course, this should be derring-do. But the misspelling is understandable given the meaning of the word and its origins.
Derring-do is pleasantly archaic and often used humorously in modern writing.* It means actions showing heroic courage or feats of daring.
The word originated from the late Middle English dorryng do (meaning ‘daring to do’) being misprinted as derrynge do in the 16th-century editions of John Lydgate’s Chronicle of Troy.
The modern usage and spelling is usually most associated with Sir Walter Scott’s Ivanhoe.
*I would love to proofread a story where derring-do doesn’t look out of place. I am imagining pirates. Or an old-fashioned superhero.
Hannah McCall 
I’ve never heard of this term before. Is it in common usage?
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It is old fashioned but it does pop up occasionally!
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Quick to read, informative and easy to understand – Loved it!
Just out of curiosity, are there any other situations where I can (or should) use “derring”?
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Thank you so much! That is an interesting question. It is my understanding that the answer is no (the word stems from a misprint that has no modern usage) but I would be pleased to hear from anyone who knows better!
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Good one. Reminds me of another one I’ve seen misused a lot. To ‘pore over’ something is to study it carefully; a ‘pour over’ is what they do at Starbucks when they’re out of brewed coffee.
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I have a draft post dealing with the very thing. Please be assured that I am not stealing your ideas.
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Oh, sorry about that. I didn’t mean to steal your thunder. This is just a topic I particularly enjoy, and, like you, I’ve encountered A LOT of these confused words/phrases in my work.
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Not at all – I really appreciate your contributions and it is good to know that I am not the only one finding it interesting!
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