sentry — English Dictionary

Noun

1. A guard, particularly on duty at the entrance to a military base.

   Examples

   Additional sentries are keeping watch for any signs of an ambush.

2. Sentry duty; time spent being a sentry.

   Usage

   • Uncountable

3. A form of drag to be towed underwater, which on striking bottom is upset and rises to the surface.

4. A watchtower.

5. An animal like a marmot tasked with alerting the pack to danger.

Noun

1. a person employed to keep watch for some anticipated event

   Synonyms

   lookoutsentinelwatchspotterscoutpicket

   Broader terms

   watchersecurity guard