The Collaborative International Dictionary of English v.0.48:

Varlet \Var"let\, n. [OF. varlet, vaslet, vallet, servant, young
   man, young noble, dim. of vassal. See Vassal, and cf.
   Valet.]
   [1913 Webster]
   1. A servant, especially to a knight; an attendant; a valet;
      a footman. [Obs.] --Spenser. Tusser.
      [1913 Webster]

   2. Hence, a low fellow; a scoundrel; a rascal; as, an
      impudent varlet.
      [1913 Webster]

            What a brazen-faced varlet art thou ! --Shak.
      [1913 Webster]

   3. In a pack of playing cards, the court card now called the
      knave, or jack. [Obs.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

varlet
    n 1: a deceitful and unreliable scoundrel [syn: rogue,
         knave, rascal, rapscallion, scalawag, scallywag,
         varlet]
    2: in medieval times a youth acting as a knight's attendant as
       the first stage in training for knighthood [syn: page,
       varlet]