Languages evolve. Words are borrowed from other languages, their meanings change, and so do their spellings.
"Entrée" refers to the starter in French, whereas in the US, it refers to the main dish.
"A date" in the sense of a romantic encounter, originates from the English use of "date" in the sense of a calendar date. The word was then borrowed back into French, this time with its English meaning (and is pronounced the same way as in English).
"Connoisseur" is spelled "connaisseur" in modern French, while English kept the old spelling.
"Con" used to be a vulgar term for the vagina in French. Today, it is mainly used as an insult to describe someone as stupid.