Precept:
noun
- a commandment or direction given as a rule of action or conduct.
- an injunction as to moral conduct; maxim.
- a procedural directive or rule, as for the performance of some technical operation.
- Law .
a writ or warrant.
a written order issued pursuant to law, as a sheriff’s order for an election. [Dictionary.com]
I used it in this recent post. An hour or two later, I ran across the related preceptor in story The Dragon Masters, by Jack Vance, from which I shall forgo quoting.