The Collaborative International Dictionary of English v.0.48:

Enjoin \En*join"\, v. t. [imp. & p. p. Enjoined; p. pr. & vb.
   n. Enjoining.] [F. enjoindre, L. injungere to join into,
   charge, enjoin; in + jungere to join. See Join, and cf.
   Injunction.]
   1. To lay upon, as an order or command; to give an injunction
      to; to direct with authority; to order; to charge.
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            High matter thou enjoin'st me.        --Milton.
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            I am enjoined by oath to observe three things.
                                                  --Shak.
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   2. (Law) To prohibit or restrain by a judicial order or
      decree; to put an injunction on.
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            This is a suit to enjoin the defendants from
            disturbing the plaintiffs.            --Kent.
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   Note: Enjoin has the force of pressing admonition with
         authority; as, a parent enjoins on his children the
         duty of obedience. But it has also the sense of
         command; as, the duties enjoined by God in the moral
         law. "This word is more authoritative than direct, and
         less imperious than command." --Johnson.
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The Collaborative International Dictionary of English v.0.48:

Enjoin \En*join"\, v. t.
   To join or unite. [Obs.] --Hooker.
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WordNet (r) 3.0 (2006):

enjoin
    v 1: issue an injunction
    2: give instructions to or direct somebody to do something with
       authority; "I said to him to go home"; "She ordered him to do
       the shopping"; "The mother told the child to get dressed"
       [syn: order, tell, enjoin, say]