The Collaborative International Dictionary of English v.0.48:

Precept \Pre"cept\, v. t.
   To teach by precepts. [Obs.] --Bacon.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Precept \Pre"cept\, n. [L. praeceptum, from praecipere to take
   beforehand, to instruct, teach; prae before + capere to take:
   cf. F. pr['e]cepte. See Pre-, and Capacious.]
   1. Any commandment, instruction, or order intended as an
      authoritative rule of action; esp., a command respecting
      moral conduct; an injunction; a rule.
      [1913 Webster]

            For precept must be upon precept.     --Isa. xxviii.
                                                  10.
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            No arts are without their precepts.   --Dryden.
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   2. (Law) A command in writing; a species of writ or process.
      --Burrill.
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   Syn: Commandment; injunction; mandate; law; rule; direction;
        principle; maxim. See Doctrine.
        [1913 Webster]

WordNet (r) 3.0 (2006):

precept
    n 1: rule of personal conduct [syn: principle, precept]
    2: a doctrine that is taught; "the teachings of religion"; "he
       believed all the Christian precepts" [syn: teaching,
       precept, commandment]