While strolling through the dictionary the other day I happened upon the word portcullis. This word comes (c. 1200) from old French porte (door) + coleice (sliding)- now coulisser. Well, firing up my Larousse I looked for the translation of portcullis and found that it is la herse.

Another example, double entendre. Probably came from double entente, but again, is not used in modern French.

The problem when you learn more than one language is that you can waste an otherwise productive two quiet hours of children sleeping pursuing a line of inquiry that would require a stretch to reach the weight of trivia.