Watchman (noun)

1. A person who keeps watch, especially during the night, to guard against theft or unauthorized entry.
2. A person or group of people who act as a security guard.
3. A person who is responsible for keeping watch and making sure that everything is secure.
4. A person who stands guard over a place, building, or object in order to protect it.
5. A person who is assigned to observe, keep watch, and give warning of danger.

Origin:

From middle english waccheman, wachman, wakman, equivalent to watch + man.

Examples:

1. The watchman patrolled the grounds of the factory every night.
2. The watchman made rounds every hour to check that all the doors were locked.
3. The watchman was alert and vigilant, always ready to raise the alarm if necessary.
4. The watchman had a responsibility to keep the people and property under his care safe.
5. The watchman was armed with a flashlight, a whistle, and a walkie-talkie to stay in contact with the main office.