Why “king & queen” but not “roi & reine”?
If I am not mistaken, modern English language has a large influence from Old French through the Norman invasion by William the Conqueror in 1066 and subsequent Norman monarchs.
However, the modern words used in reference to male and female rulers in a monarchy are king and queen, derived from Old English cyning and cwen respectively.
But if the new rulers brought with them their language, why aren't monarchs today called something derived from roi and reine, or something along those lines?
Is it something the new rulers chose, maybe to bring themselves closer to their new subjects? Or did the population keep calling the new rulers cyning and cwen, regardless of the language the rulers brought with them, and it simply stuck? Or is it something completely different?
Solution 1:
Even if "William the Conqueror" thought himself Guillaume, roi d'Angleterre, most of his English subjects would have no idea what a roi d'Angleterre was, much less a Guillaume. No doubt William wanted to be known as just the next king, not the founder of a new order. But I think that was not the reason "king" remained in English.
The English terms "earl", "sheriff" and "knight" were retained by the Norman rulers to promote continuity. French terms were used for concepts not previously part of English government such as "marquess". (Some concepts were mixed, like "duke". Some French terms were alternatives to English terms, like "count".)
It would be obvious here that the Normans were more interested in exploiting the English apple cart than upsetting it. They actually did both, but not by attempting to turn England into Normandy. Even if William were King of England and Duke of Normandy, England and Normandy remained separate concerns.
It cannot be surprising that "king" and "queen" remained in English given the Norman attitude.
Solution 2:
William claimed the existing title of King held by Harold. French became less popular in large part due to the 100 years war. Henry IV was the first to take his oath in English. Henry V was a native English speaker.
The last thing William wanted was to invent a new title and leave the title "King of England" open to be claimed by one of his many enemies and rivals. The whole point of the Norman conquest was to claim the title "King of England" for William.
Solution 3:
One reasonable explanation is that the Normans wanted to be seen as the legitimate heirs to an existing title rather than as conquerors who granted themselves a new title.
Having said that the key legal terms and adjectives such as monarch, crown, sovereign and royal are all Latin or Old French in origin.
This can also be related to the fact that terms for livestock tend to have Old English origins (Cow, Pig etc) while terms for meat as food tend to be french.