watch ‧ dog /ˈwɒtʃdɒɡ $ ˈwɑːtʃdɒːɡ, ˈwɒːtʃ-/ BrE AmE noun [countable]
1 . a person or group of people whose job is to protect the rights of people who buy things and to make sure companies do not do anything illegal or harmful:
a consumer watchdog
2 . old-fashioned a ↑ guard dog