The Nuttall Encyclopedia
Cachet, Lettre de
A warrant issued in France before the Revolution, under the royal seal, for the arrest and imprisonment of a person, often obtained to gratify private ends; abolished in 1790.
Wood, James, ed. Entry for 'Cachet, Lettre de'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/c/cachet-lettre-de.html. Frederick Warne & Co Ltd. London. 1900.