IPA: /pəˈliːsər/
KK: /pəˈlisər/
A person or thing that enforces laws or regulations, typically in a specific area or context.
The policer ensured that the rules were followed during the event.
The word 'policer' originates from the Old French 'police' (meaning public order or government) and the suffix '-er' (meaning a person who). A policer is a person who maintains public order or enforces the law.
Think of someone who is part of maintaining 'public order' ('police') — the '-er' indicates that this person is actively involved in that role.