Raison d’etre is French for reason of being. In English, we use it to mean a reason for the existence of a person or thing. In reference to people, it often describes one’s driving passion. For example, if you feel the reason you get up in the morning is to work in your garden, then gardening is your raison d’etre.
You may sometimes see the circumflex (the pointy-hat accent mark) above the first e—raison d’être. The mark is proper in French, but English isn’t kind to these accent marks, even when it comes to French loanwords, so including the circumflex is optional.
Having made fuel aid the raison d’etre for a winter event, council members began poking fun at the stereotype of elder citizens hunched over their bingo cards. [Boston Globe]
Android’s whole raison d’être is to be the more open alternative to Apple. [Pando Daily]
The Hanseatic League’s raison d’être was to establish and defend special trade privileges for its members throughout northern Europe. [Financial Times]
This is an essential function, but the raison d’être of a college is to nourish a world of intellectual culture. [New York Times guest commentary]
As for the Tories, there is a minimal excuse because constitutional conservatism is their political raison d’être. [Scotsman]