noun
A person assigned to watch over a place, activity, or people for safety, security, or supervision. Common in contexts like swimming pools, construction sites, and surveillance.
プールの監視員はいつも子供たちを見守っている。
The pool lifeguard is always watching over the children.
工事現場には監視員が配置され
A watchman is stationed at the construction site.
警備員 is a security guard, often with a broader role in guarding property and maintaining order, whereas 監視員 focuses on observation and monitoring.
Compound of 監視 (kanshi, 'monitoring') + 員 (in, 'member' or 'personnel'), literally 'monitoring person'.