1. Fillet (French: filet)
How we pronounce it: fillay
How it’s pronounced: filleh
Perhaps the most common mispronunciation of French loanwords is turning the final E in words that end in “et” or “é” into an “ay” diphthong. This can also be seen in words such as buffet (bouffeh in French, buhffay in English), as well as this following word:
How we pronounce it: ontray
How it’s pronounced: untreh
This is a prime example, because we have here both a mispronunciation, as well as a widely divergent meaning. In French, entrée means “entrance”, and in the context of food- a starter, whereas in English it came to mean the main course.
3. Hors d’oeuvres
How we pronounce it: or durves
How it’s pronounced: or doovre
Another way to refer to an appetizer or starter, here we can see an example of metathesis, a linguistic phenomenon where consonants are interchanged for ease of pronunciation, as “vr” isn’t a common consonant cluster in English, particularly in the final position, while “rv” is far more palatable (serve, swerve, and in UK English- turves).
4. Déjà vu
How we pronounce it: day javoo
How it’s pronounced: déjà vu
Probably less offensive a mangling than the other contenders, the stress in the English pronunciation is nevertheless all wrong, due to the elongated “ay” diphthong. Try pronouncing the words separately for a better approximation.
How we pronounce it: gilliotine
How it’s pronounced: giyotine
Just like Spanish "pollo", the “ll” grapheme in French, when followed by a vowel produces a “y” sound. This is preserved in the English pronunciation, however without actually discarding the “l” sound.
6. Coup de Grâce
How we pronounce it: coo de gra
How it’s pronounced: coo de grahss
Staying on the grisly topic of execution, this is a rather amusing case of what’s called hypercorrection, a mispronunciation born out of a desire to say the word the “proper” and “authentic” way. Some people figured that, because French often drops the final consonant, the “-ce” in this idiom should be silent. The result is that, instead of delivering a blow of mercy, you dish out a stroke of fat or grease.
7. Double entendre (in French: à double sens)
How we pronounce it: dubbel uhntundray
How it’s pronounced: ah dooble sunse
In this case, it’s not merely a problem of mispronunciation, as this particular term doesn’t actually exist in French. Taken as is, double entendre would mean something like “double to hear” which is grammatically incorrect. "À double entente" could be used to refer to a word or phrase with a double meaning, though "à double sens" is a far more common way of saying this.
As you might imagine, this doesn’t refer in French to a sheer nightgown, but is rather a particularly rude way of referring to the woman wearing it as somehow “neglected”. In French, the sexy nightwear is actually known as déshabillé, literally “undressed”.
How we pronounce it: shagrin
How it’s pronounced: shagrun
Whereas in English "much to my chagrin" expresses consternation or exasperation, in French it means a deep sense of sorrow and woe. This not-quite-exact relationship between two words with a shared etymology is what's called faux amis, or "false friends". The reason the term is in French is because English and French have a lot of these false friends.
10. À la mode
In French, this phrase means “in the fashion of”, but never “with a scoop of vanilla ice cream on top”. If you were to ask for a tart à la mode, the only thing you would receive is a blank stare or a condescending smirk.