Any living language is a dynamically developing phenomenon. And one of the ways of development is borrowing. If you understand the system and methods of borrowing words, then the meaning of the word "comme il faut" will not be difficult to establish.
In any (especially European) language, there are very few native words and roots exclusively, because the languages of Europe for centuries closely interacted with each other and with the languages of Asia, Africa, America and Australia (due to colonization).
Foreign lexemes can come into the language both to designate new phenomena and as new names for old phenomena. For example, in many languages there are words (sputnik, cranberry, vodka, cabbage soup, borscht, gingerbread and others that name objects of traditional Russian life). Words that have passed into international culture are borrowings from Russian. Just as Russian children wonder what the word "comme il faut" means, French children wonder about borscht until they try it.
Borrowing can be of two kinds. First, there is a more or less exact phonetic copying of a word and its natural adaptation for morecomfortable pronunciation. Secondly, the division of the constituent parts of a word or expression and the translation of parts of the word into the language into which the borrowing occurs. So, more often they borrow complex, multi-root words or whole expressions. Often, in order to identify such borrowing, one must have an extensive linguistic outlook or a phenomenal linguistic instinct.
For example, few people realize that the word "Orthodox" is a tracing paper borrowing from the Greek word "orthodox". Over the centuries, borrowings from the languages of other peoples have come to the Russian language.
A brief history of borrowings is as follows: In the X-XII centuries, a lot of Greekisms appeared, that is, roots that came from Greek, especially in the church sphere. In the XII-XIV centuries, the Turkisms came: the Mongol yoke could not pass without a trace for the language.
Next - the Time of Troubles, Cossack riots, Schism - and close interaction with the Commonwe alth. Polonisms appear in Russian - that is, borrowings from the Polish language. Then, of course, the meaning of the word "comme il faut" was not yet known.
Peter I was very fond of Dutch and German culture, and this also did not go unnoticed for the Russian language, echoing a number of Germanisms, especially in the military and shipbuilding spheres.
In the second half of the 18th and in the 19th century, as you know, everyone was crazy about France and all French culture in general. Any child then knew the meaning of the word "comme il faut": "good tone, the rules of decency." Translated from French, the phrase "comme il faut"means "as needed". Gallicisms were not long in coming and occupied many areas of life - military, court, art, fashion.
Sometimes we don't even see Gallicisms in our native language: battalion, boa, marmalade, tights, broth, comme il faut. The importance of Gallicisms for the Russian language is difficult to exaggerate. They undoubtedly enriched our language with a variety of sound combinations. But now, unfortunately, many people have begun to forget the meanings of some borrowings, and this is not comme il faut! The meaning of a word is the least you need to know about it.
Well, the 20th century is famous for Anglicisms and Americanisms. They came with jeans and McDonalds, they came with skinny models and iPhones, they came from overseas with rock culture and dollars.
Undoubtedly, the 21st century, the first century of the new millennium, will also bring us new phenomena and invariably new borrowings.