sentinel

US /ˈsen.t̬ɪ.nəl/
UK /ˈsen.t̬ɪ.nəl/
1.

lính gác

a soldier or guard whose job is to stand and keep watch.

1.

đặt người nào gác

station a soldier or guard by (a place) to keep watch.

:
a wide course had been roped off and sentineled with police