The French don't curse more than anyone else, and our swear words aren't French, so why do we say "Pardon my French" when we use offensive words?
Bonjour! Today we're discussing some historical and linguistic connections between French and English, covering topics as varied as the Bastille, frogs’ legs, and roast beef. We'll also learn why we say "pardon my French," but in order to do that, we first need to take a closer look at the historic connection between England and France.
What is a bastille, you may ask? For those who don’t know much French or who haven’t studied European history lately, here’s a mini-lesson. “Bastille” is the French word for “fortress” or “castle.”  It’s also the name of the famous building that revolutionaries stormed on July 14, 1789, at the beginning of the French Revolution. The Bastille was built in the 1300s to protect Paris from the English. Its 100-foot walls later held political prisoners, including the French writer Voltaire.
The French celebrate their national holiday on July 14. In the United States, it is called Bastille Day. In France, it is not. In France, July 14 is known by what translates as “The National French holiday,” and the French wish each other “Happy National Holiday,” not “Happy Bastille Day.” On every Bastille Day since 1880, there has been a military parade in Paris.
France vs. England
The French and English haven’t always been allies, as they are today, and the Bastille was originally built to protect the French from the English. The two countries have had a long history of conflict—in fact, about 900 years of conflict! In 1066, William the Conqueror of Normandy, France, invaded England and defeated the English at the Battle of Hastings. Since this pivotal moment, the French and English languages have been intertwined.
One reason English has so many synonyms is that it absorbed thousands of words from French.
The Norman Conquest of England greatly affected the English language. About 10,000 or so French words came into English after the Conquest, and about three-quarters of them are still in use today. In fact, English has many pairs of words—one from Old English and the other from French— that mean about the same thing. One example is “law” and “order.” “Law” comes from an Old English word in use before the year 1000; it came to English from Old Norse. “Order” has later origins, coming to Middle English via Old French and Latin between 1175 and 1225. Another example is “forgive” and “pardon.” “Forgive” was in use before the year 900 and comes from Middle and Old English. “Pardon” is from Old French and has been used in English since the middle of the 15th century. Finally, consider “ask” and “inquire.” “Inquire” comes from Old French, and “ask” comes from Old English.
Experts today sometimes say you can improve your writing—or at least make it more clear and straightforward—by favoring words with an Old English origin, but long ago in many cases, using a word with a French origin was thought to be more refined than using a similar word with an English origin.