sentry

Từ điển tiếng Anh - Cambridge Advanced Learners Dictionary

sentry UK US [ˈsen.tri] noun countable [ sentries ]
a soldier who guards a place, usually by standing at its entrance
• My squad were on sentry duty last night.
Thesaurus⁺: ↑Protection and protectors ↑Environmental issues ↑Soldiers and people who fight in wars

• Từ đồng nghĩa / Synonyms:
  lookout, lookout man, sentinel, watch, spotter, scout, picket