The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

Standing out there like a glorified SENTRY.
Game of Thrones Season 1, Episode 3

QA Sentry:
Freeze all motor--
Westworld Season 2, Episode 10

-(SENTRY MECH WHIRS)
-Maybe we should turn back.
Westworld Season 3, Episode 8

SENTRY MECH: Disperse. Disperse.
Westworld Season 3, Episode 8