The Collaborative International Dictionary of English v.0.48:

Perk \Perk\ (p[~e]rk), v. t. [imp. & p. p. Perked (p[~e]rkt);
   p. pr. & vb. n. Perking.] [Cf. W. percu to trim, to make
   smart.]
   To make trim or smart; to straighten up; to erect; to make a
   jaunty or saucy display of; as, to perk the ears; to perk up
   one's head. --Cowper. --Sherburne.
   [1913 Webster]

   to perk up one's ears to begin to listen attentively; --
      usually used when something of interest is mentioned in
      some discourse, after one's attention had lapsed; as, he
      perked up his ears when he heard his name mentioned.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Perk \Perk\, v. i.
   1. To exalt one's self; to bear one's self loftily. "To perk
      over them." --Barrow.
      [1913 Webster]

   2. To act in a jaunty or presumptuous manner.
      [PJC]

   To perk it, to carry one's self proudly or saucily. --Pope.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Perk \Perk\, a.
   Smart; trim; spruce; jaunty; vain. "Perk as a peacock."
   --Spenser.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Perk \Perk\, v. i.
   To peer; to look inquisitively. --Dickens.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

perk \perk\, n.
   A perquisite. [informal]
   [PJC]

WordNet (r) 3.0 (2006):

perk
    n 1: an incidental benefit awarded for certain types of
         employment (especially if it is regarded as a right); "a
         limousine is one of the fringe benefits of the job" [syn:
         fringe benefit, perquisite, perk]
    v 1: gain or regain energy; "I picked up after a nap" [syn:
         perk up, perk, percolate, pick up, gain vigor]