Source : Webster's Revised Unabridged Dictionary (1913)

Knave \Knave\, n. [OE., boy, servant, knave, AS. cnafa boy,
   youth; cf. AS. cnapa boy, youth, D. kna?p, G. knabe boy,
   knappe esquire, Icel. knapi, Sw. knape esquire, kn["a]fvel
   knave.]
   1. A boy; especially, a boy servant. [Obs.] --Wyclif.
      Chaucer.

            O murderous slumber, Lay'st thou thy leaden mace
            upon my boy That plays thee music ? Gentle knave,
            good night.                           --Shak.

   2. Any male servant; a menial. [Obs.] --Chaucer.

            He's but Fortune's knave, A minister of her will.
                                                  --Shak.

   3. A tricky, deceitful fellow; a dishonest person; a rogue; a
      villain. ``A pair of crafty knaves.'' --Shak.

            In defiance of demonstration, knaves will continue
            to proselyte fools.                   --Ames.

   Note: ``How many serving lads must have been unfaithful and
         dishonest before knave -which meant at first no more
         than boy -- acquired the meaning which it has now !''
         --Trench.

   4. A playing card marked with the figure of a servant or
      soldier; a jack.

   {Knave child}, a male child. [Obs.] --Chaucer.

   Syn: Villain; cheat; rascal; rogue; scoundrel; miscreant.