a soldier whose job is to guard something synonym sentry哨兵 - (figurative)
a tall round tower standing sentinel over the river 镇守在河边的一座高高的圆塔 Large dark pines stood like sentinels guarding the wintry garden. 巨大的黑松像哨兵一样守卫着冬天的花园。
Word Originlate 16th cent.: from French sentinelle, from Italian sentinella, of unknown origin.- (figurative)