"Merci" is how you say "thank you" in which language?
Of course, in the following...
✴️ Armenian
✴️ Bulgarian
✴️ Catalan
✴️ Farsi (Persian)
✴️ Luxembourgish
✴️ Romanian
✴️ Swiss German
oh, and in French (I almost forgot).
It's true! Bulgarian, for instance, adopted "merci" in the 1930s, first ironically, but eventually as a simple and "sophisticated" alternative to the relatively formal "blagodarya".
I had to laugh the first I heard a Bulgarian say "merci mnogo" ("thanks very much"), and note that unlike in French, the Bulgarians roll the "r".
Note that in most of these languages "merci" is only one of the options for saying "thank you". It's often the informal version, much like "thanks", "ta" or "cheers" in English.
Мерси много за вниманието!
Picture: "merci" in Farsi