Entry 1 sense Webster, 1913 Watchdog /(wŏch"dŏg`)/ · Watch·dog · IPA /ˈwɑːt͡ʃˌdɑːɡ/ 01 n. A dog kept to watch and guard premises or property, and to give notice of the approach of intruders. 1. A dog kept to watch and guard premises or property, and to give notice of the approach of intruders.