noun, plural bil·lets-doux [bil-ey-dooz, bil-ee-; French bee-yey-doo] /ˈbɪl eɪˈduz, ˈbɪl i-; French bi yeɪˈdu/.
Examples from the Web for billet-doux
A papal excommunication is a billet-doux compared to the Commination of Jugana.The Lock And Key Library|Various
Adonis calls for a "pick-me-up" before he has strength enough to answer a billet-doux from Venus.Kenelm Chillingly, Complete|Edward Bulwer-Lytton
Oh, you have not heard of the billet-doux that Schwarzfelder has written you?In Hostile Red|Joseph Altsheler
We may fancy Madame La Croix slyly handing the billet-doux to the daughter, under the unsuspecting mother's very eyes.The Anglo-French Entente in the Seventeenth Century|Charles Bastide
Remember that this is the first time I ever wrote a billet-doux, and I dont know how they are usually expressed.The Bashful Lover (Novels of Paul de Kock Volume XIX)|Charles Paul de Kock