noun

sentry

SEN-tree/ˈsentri/

A guard stationed to watch for danger or unauthorized entry.

A sentry stands at the gate and watches for intruders.

A uniformed sentry stands at a closed security gate beside a small guard booth, watching the approach with binoculars held ready.

Etymology

Sentry first denoted a defensive watchtower and later a guard posted on watch. Its uncertain origin may connect it with sentinel, or with sanctuary through the idea of shelter for a watchman.

In context

Storytime Haven341:41

It is kept in a safe in the chief steward’s cabin, and, while it is on board, a sentry is always on duty at the door.

A Prince of Swindlers 👑💰 | A Tale of Deceit and Adventure by Guy Boothby

More examples

The sentry checks our passes before letting us enter.
Two sentries keep watch while the other soldiers sleep.
The sentry sounds the alarm when strangers approach the camp.

Forms

sentry · sentries

Similar words

sentinel: Often suggests a formal military or ceremonial watch.
watchman: Usually watches a building or property, especially at night.
guard: Covers broader protective duties, not just a fixed watch.