lettre de cachet

from Wiktionary, Creative Commons Attribution/Share-Alike License

• n. A warrant issued by the monarch in ancien régime France, especially one which imprisons someone without trial.

from the GNU version of the Collaborative International Dictionary of English

• n. a sealed letter, especially a letter or missive emanating from the sovereign; -- much used in France before the Revolution as an arbitrary order of imprisonment.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• n. a warrant formerly issued by a French king who could warrant imprisonment or death in a signed letter under his seal