watchdog

Short definition from Wiktionary

Noun

1. 1
   A guard dog.
2. 2
   An individual or group that monitors the activities of another entity (such as an individual, corporation, non-profit group, or governmental organization) on behalf of the public to ensure that entity does not behave illegally or unethically.
3. 3
   Ellipsis of watchdog timer.

Verb

1. 1
   To perform a function analogous to that of a watchdog; to guard and warn.
2. 2
   To be continuously reset by a watchdog timer.