Synonym for policeman/policewoman?

Solution 1:

A police officer can be referred to by several titles.

• Officer can be a generic term not denoting rank, position, or job function. Although it usually refers to a patrolman regardless of the patrolman’s rank (officer, corporal, sergeant, etc.)
• Patrolman can refer to a uniformed police officer, usually on patrol.
• Cop is an obvious choice.
• Copper is a little antiquated.
• LEO is short for Law Enforcement Officer. Many states and departments use this term to identify someone as a certificated and registered police officer.
• Five-O if you are street.

Solution 2:

"Cop, "police officer," "law enforcement officer," or "law enforcement agent" could all work, but "cop" is likely the best choice.

Cop: A police officer. [Lexico]

Police officer: A policeman or policewoman. [Lexico]

Law enforcement officer: A government employee appointed to enforce the law, such as a police officer or sheriff. [Lexico]

Law enforcement agent: A police officer [Macmillan]

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Solution 3:

Police officer doesn't suggest any particular rank or type—any member of the police force can be referred to by that term:

[Merriam-Webster]
: a member of a police force
// there were police officers directing traffic around the scene of the accident

More informally, there is simply officer (again, no rank or type in this context) or cop, and slang terms, some with regional bias, include copper, flatfoot, and bobby.