'Watchdog' definitions:

Definition of 'watchdog'

From: WordNet
noun
A guardian or defender against theft or illegal practices or waste; "she is the global watchdog for human rights abuses"
noun
A dog trained to guard property [syn: watchdog, guard dog]

Definition of 'Watchdog'

From: GCIDE
  • Watchdog \Watch"dog`\ (w[o^]ch"d[o^]g`), n. A dog kept to watch and guard premises or property, and to give notice of the approach of intruders. [1913 Webster]