The Collaborative International Dictionary of English v.0.48:

Savvy \Sav"vy\, Savvey \Sav"vey\, v. t. & i. [Written also
   savey.] [Sp. saber to know, sabe usted do you know?]
   To understand; to comprehend; know. [Slang, U. S.]
   [Webster 1913 Suppl.] Savvy

The Collaborative International Dictionary of English v.0.48:

Savvy \Sav"vy\, Savvey \Sav"vey\, n.
   Comprehension; knowledge of affairs; mental grasp; also,
   practical know-how; common sense. [Slang, U. S.] also adj.
   knowledgeable; well-informed; clever; canny; wise.
   [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

savvy
    n 1: the cognitive condition of someone who understands; "he has
         virtually no understanding of social cause and effect"
         [syn: understanding, apprehension, discernment,
         savvy]
    v 1: get the meaning of something; "Do you comprehend the
         meaning of this letter?" [syn: grok, get the picture,
         comprehend, savvy, dig, grasp, compass,
         apprehend]