To mention, in English, the French mathematician Guillaume de l'Hôpital only with the surname, should I use De l'Hôpital or de l'Hôpital? Should I use other combination?

I would use the reference that one answer of Using English naming customs for foreign names suggest, but it is not an open source and this specific question is not solved there.


1 Answer 1


About multipart names, Prof. Paul Brians of Washington State University says:

In many European languages family names are often preceded by a preposition (de, da, di, von, and van all mean “of”), an article (le and la mean “the”) or both (du, des, del, de la, della and van der all mean “of the”).

In their original languages the two parts of the name are usually separated by a space, and the prefixed preposition or article is not capitalized unless it begins a sentence. If you take a college course involving famous European names you will be expected to follow this pattern. It’s not “De Beauvoir” but “de Beauvoir”; not “Van Gogh” but “van Gogh.” The only exception is when the name begins a sentence:

  • De Gaulle led the Free French


  • Charles de Gaulle had a big nose.

Quoting Mark Stevens, the director of general reference at Merriam-Webster’s, Grammarphobia says:

In the names of Frenchmen and -women, de and d’ are almost always lowercased; treatment of du varies. La and Le are almost always capitalized.

With Guillaume de l'Hôpital, the difficulty is whether to mention the surname including or omitting de. The internet uses more than one variant at the beginning of a sentence, but most sites omit the de, and capitalise L:

Since all mathematicians speak about L'Hôpital's Rule, also spelled as L'Hospital's rule, I would go for L'Hôpital, whether it is at the beginning or in the middle of the sentence.

  • A possible exception is when of is shortened to O', for example John of Gaunt to John O'Gaunt. Aug 10, 2022 at 10:10
  • Yes, correct, but we are speaking here about the particular case of the French de l'.
    – fev
    Aug 10, 2022 at 10:11
  • Sorry: your examples mention de and d' (Charles de Gaulle), and "the prefixed preposition or article is not capitalized unless it begins a sentence". Aug 10, 2022 at 10:13
  • So, according to the last reference, it should be de L'Hôpital because de is not capitalized but Le is and it is in the contracted form, right?
    – MathBug
    Aug 10, 2022 at 10:26
  • I have edited my answer. Basically, most people omit the de and then L'Hôpital falls under the capitalisation of "L" rule.
    – fev
    Aug 10, 2022 at 10:29

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