noun | [ˌbɪleɪ ˈdu:]
a love letter 情书
Did you Know?
法语单词biilet doux第一次出现在英语中，是在约翰·德莱顿（John Dryden）1673年的戏剧“Marriage a-la-Mode”中。在剧中，德莱顿通过一个喜剧角色Melanthe来取笑英国社会中的语言亲法者（Francophile）。其中，她未来的爱人Rodophil这样描述她：
No lady can be so curious of a new fashion as she is of a new French word; she's the very mint of the nation, and as fast as any bullion comes out of France, coins it immediately into our language.
Let me die, but he's a fine man; he sings and dances en Français, and writes the billets doux to a miracle.
Examples of BILLET-DOUX
While cleaning out her parents' basement, Amy stumbled upon a box containing billets-doux written by her dad to his high-school sweetheart—her mom.
"… when you stop to think about it the entire panoply of behaviours we consider as romantic, from sending little billets-doux, to developing a shared vocabulary of pet names, are … infantile. What's romance, then, but a kind of childish make-believe?"
— Will Self, Prospect, 13 Oct. 2016