Source : Webster's Revised Unabridged Dictionary (1913)

Perk \Perk\, v. t. [imp. & p. p. {Perked}; 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.