valvekoer tähendus null.

watchdog [watchdogs]▼◼◼◼noun
[UK: ˈwɒtʃ.dɒɡ] [US: ˈwɑːʧ.ˌdɔːɡ]

guard dog▼◼◼◼[UK: ɡɑːd dɒɡ] [US: ˈɡɑːrd ˈdɔːɡ]