Sentry Gun Edit Meaning

1.

Any stationary weapon capable of indentifying and assaulting individual targets without the aide of human operators.

"The sentry gun could track up to five targets simultaneously."

2.

In TFC, a machinegun on a tripod that shoots on its own. Built by an engineerand avoided/destroyed by a disguised spy

"Somebody take out the sentry gun in the flag room!"

"We need a sentry gun in the flag room!"