"Naïve" is a perfectly valid English word. (If your mail reader doesn't
display this correctly: that's an i with two dots on top instead of one)
Likewise is "coup d'état" an English word (e with accent). All loan
words from French, but nontheless English words.
Yes, but in importing such words into English, we're perfectly happy to
strip off the "decorations" that you mention. For example, when I look up
naïve in Webster's New Universal Unabridged Dictionary (a large book, not an
online service) it lists both the decorated and undecorated versions, with
the undecorated version appearing first, indicating the more common usage.
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