DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   spying
       n 1: keeping a secret or furtive watch
       2: the act of keeping a secret watch for intelligence purposes
          [syn: spying, undercover work]
       3: the act of detecting something; catching sight of something
          [syn: detection, catching, espial, spying,
          spotting]