What is Commandment?

Legal Definition
In practice. An authoritative order of a judge or magisterial officer. In criminal law. The act or offence of one who commands another to transgress the law, or do anything contrary to law, as theft, murder, or the like. Particularly applied to the act of an accessary before the fact, in inciting, procuring, setting on, or stirring up another to do the fact or act 2 Inst. 182.
-- Black's Law Dictionary
Legal Definition
An old English offence of directing one to do an unlawful act.
-- Ballentine's Law Dictionary