The Collaborative International Dictionary of English v.0.48:

Nab \Nab\, v. t. [imp. & p. p. Nabbed (n[a^]bd); p. pr. & vb.
   n. Nabbing.] [Dan nappe, or Sw. nappa.]
   1. To catch or seize suddenly or unexpectedly. [Colloq.]
      --Smollett.
      [1913 Webster]

   2. To capture; to arrest; as, the police nabbed the culprit
      wtrying to hide in the basement.
      [PJC]