Cāch'et, n.

(kāsh'ā), n. [Fr. cachet, from cache, cacher. See CACHE.] A seal, as of a letter.

Lettre de cachet, a sealed letter, especially a letter or missive emanating from the sovereign, signed by him and countersigned by a secretary of state, folded in such a manner that the contents could not be read without breaking the seal. It was formerly much used as an instrument of imprisoning those who gave offense to the king of France or his chief ministers. Bescherelle.