Is there a preferred word that means "to change (a word) to sound (or otherwise appear) as if it came from French"? I've found both "Frenchize" and "Francize" with a web search. If the latter is preferred, I'm not sure whether it takes a soft "C".
Come to think of it, the same could be asked of any language. It would be interesting to have a list like this.
Even more interesting would be to have a general term for the conversion (possibly surreptitious, as of a surname) from one language to another.
Edit: Here's a list of whatever we come up with.
English → Anglicize
French → Gallicize
German → Germanize
Greek → Grecize