Definition of lettre de cachet in US English:

lettre de cachet

noun

  • An official order for imprisonment, exile, or some other punishment; specifically (in pre-revolutionary France) a warrant issued for the imprisonment of a person without trial at the pleasure of the monarch.

Origin

Early 18th century; earliest use found in William Darrell (1651–1721), Jesuit. From French lettre de cachet from lettre + de + cachet.

Pronunciation

lettre de cachet

/ˌlɛtr(ə) də ˈkaʃeɪ/