A person who is employed to provide security for people or property.
2018 February, Robert Draper, “They are Watching You—and Everything Else on the Planet: Technology and Our Increasing Demand for Security have Put Us All under Surveillance. Is Privacy Becoming just a Memory?”, in National Geographic[1], Washington, D.C.: National Geographic Society, →ISSN, →OCLC, archived from the original on 14 June 2018:
Haz sits in the trailer for 10 hours straight, eyes trained on the patrons. If he sees the makings of a drug deal or a fight, he notifies the club’s in-house security by walkie-talkie. It amazes him how indiscreet drug dealers can be—with the bulges in their socks and their melodramatic handovers—despite the presence of security guards.
security guard on Wikipedia.Wikipedia 