a formal order under seal, issued in the name of a sovereign, government, court, or other competent authority, enjoining the officer or other person to whom it is issued or addressed to do or refrain from some specified act.
b.
(in early English law) any formal document in letter form, under seal, and in the sovereign's name.
O.E. writ "something written, piece of writing," from the past participle stem of writan (see write). Used of legal documents or instruments since at least 1121.