sentinel
noun /ˈsentɪnl/
/ˈsentɪnl/
(literary)- a soldier whose job is to guard something synonym sentry
- (figurative) a tall round tower standing sentinel over the river
- Large dark pines stood like sentinels guarding the wintry garden.
Word Originlate 16th cent.: from French sentinelle, from Italian sentinella, of unknown origin.