What is the umlaut-esque diacritical mark used over the i in naïve and Aïda called?
diaeresis.
I believe it’s called a diaeresis. It’s not just French, BTW. Some English words (coöperate) used to take them, too. The marks indicate that the vowel is to pronounced separately instead of a dipthong (co-operate instead of coop-erate). My Chicago Manual says their used in Portugese and Spanish, but only in that sort of special case.
In case you mean what is called in French, it is le tréma.
“Umlaut-esque”? I thought the umlaut and the diaeresis were exactly the same thing. What’s the diff?
My wife (who grew up in France) has confimed missbunny’s answer.
Moral of the story: consult your wife first, even when you’re living in different places.
I think it’s just a matter of application. I only know of umlauts being used in German, and they only go over a, o, and u. The appearance (the side-by-side dots) is the same though.
Umlauts and diaereses look the same but have a different function. An umlauts changes the sound of the vowel it’s are over. A diaeresis is a signal as to the proper syllabification.
In Swedish and Finnish, ä and ö are neither diaereses nor umlauts. They are considered distinct letters in those languages and are alphabetized as the last two letters in the alphabet.