One who is holding a captive or captives.
One who catches or has caught or captured something or someone.
A guard, particularly on duty at the entrance to a military base.
A animal like a marmot tasked with alerting the pack to danger.
Sentry duty; time spent being a sentry.
A watchtower.
A form of drag to be towed underwater, which on striking bottom is upset and rises to the surface.