Savoir-faire is the knowledge of what to do in any situation, or tact. The term entered English from French in the early 1800s. Its literal translation is “knowing how to do.” In English, this loanword is often used to describe social tactfulness, but in French this is just one of many terms in the lexicon of social refinement. Savoir-vivre is the knowledge of the ways of polite society, translating literally to “knowing how to live.”

Ennui stems from the Old French word enui meaning “displeasure” or “annoyance.” Ultimately, these terms, as well as the English term annoy, can be traced to the Latin in odiō meaning “hated.” Today ennui means weariness or discontent from lack of interest, or boredom, in both French and English alike.

The French call someone who enjoys indulging in food, drink, and the finer things in life a bon vivant, which translates to “well-living man.” The feminine variant is bonne vivante. Bon vivant doesn’t quite have an English equivalent, which is why English speakers borrowed from the French, who know a thing or two about the good life.

Carte blanche comes from the French card game piquet, which became popular with the English in the mid-1600s. In the game, a carte blanche was a hand with no face cards. Over time its meaning evolved to include signing a blank paper without the stipulations written on it, thus paving the way for its contemporary definition: having unconditional authority.

Je ne sais quoi is just as mysterious as it sounds. This term, which translates to “I don’t know what,” means “an indefinable, elusive quality, especially a pleasing one.” Borrowed in the mid-1600s, this phrase initially referred to any mysterious trait. Today, je ne sais quoi is largely used to discuss pleasing characteristics.

Avant-garde was first borrowed from French in the 1400s as a military term. It translates literally to “advance guard” and shares linguistic roots with the term vanguard. In the early 1900s, avant-garde began to be used in English to refer to artistic innovation. This meaning is more relevant now, as avant-garde is often used to refer to artists, writers, or musicians whose techniques and ideas are markedly experimental or ahead of the curve. The term is also used as an adjective to mean “radical, daring.”

Trompe l’oeil is an artistic technique of visual deception in which illusion is achieved using extreme detail to make flat surfaces such as canvases and walls appear three-dimensional. Trompe l’oeil translates literally as “fools the eye.” Even though the word has only been on loan since the late 1800s, the trompe l’oeil technique dates all the way back to the early Renaissance.

A femme fatale is an irresistibly attractive woman who leads men to their downfall. While the archetype of dangerously sexy women has existed for quite some time, femme fatale, French for “fatal woman,” became popular in English in the late 1800s. The femme fatale has since become a quintessential film noir character and stock James Bond villain.

Nouveau riche, French for “new rich,” is a recently wealthy individual or class. This term entered English around 1800 and gained new relevance in the United States during the Gilded Age, a period of rapid economic growth in tandem with poverty and social inequity. Nouveau riche is often used pejoratively to characterize ostentatious spending tastes.

Many English speakers recognize cul-de-sac to mean a street that is closed at one end. However, this French term was first borrowed by anatomists in the 1700s to describe the first part of the large intestine, or “blind gut,” which, behind the opening of the ilium, is closed on one end. The road definition we’re familiar with today became popular a little over half a century later. Cul-de-sac, literally meaning “bottom of the bag,” is less popular among the French, who prefer to use impasse.