rhizoverbBeta
DictionarysentinelWatcher or early warning
noun / adjective

sentinel

SEN-tih-nul/ˈsentɪnl/

A watcher or indicator of danger or change.

The sentinel scans the approach through binoculars from the secured gate.

A uniformed guard stands alone at a secured perimeter gate, scanning the approach through binoculars beside a small guard booth.
Etymology
sentinelItalianguard

Italian sentinella already meant a guard. A possible connection with hearing or perceiving would fit a watchman’s task, but this deeper ancestry has not been convincingly established.

In context

US National Archives10:06
Every cell had a sentinel posted at it to be relieved every two hours.
The Lincoln Lectures — The Lincoln Assassination Conspirators: Their Confinement and Execution ...

More examples

  • The sensor acts as a sentinel for dangerous gas leaks.
  • Sentinel species can reveal pollution before people notice its effects.
  • Two sentinels watch the entrance throughout the night.

Forms

sentinel · sentinels

Similar words

lookout
Usually a person actively watching for approaching danger.
indicator
Signals a condition or change without necessarily watching for danger.
monitor
Observes or measures conditions continuously, not necessarily for early warning.