The Chinese word for policeman is
警察

jǐng chá

Chinese Definition

policeman
1. 警察
2. 警官
Components
警
1. to warn; to admonish
警告 - to warn -
2. to be on the alert; to be vigilant
警覺jué - vigilance -
3. intuitive; sharp; alert
4. aphoristic; epigrammatic; witty
5. alarm; alert; siren
火警 - fire alarm -
6. Short for 警察, police
警車 - police car -
交通警 - traffic police -
察
1. to examine; to investigate; to notice
2. Short for 察哈爾
^晉 ^察 ^冀 ^邊區 - Shanxi-Chahar-Hebei Border Region

警察
1. n. police; police force
警察暴力 - police brutality
警察用武力驅趕示威者。 - The police cleared out the demonstrators by force.
街.上shang 躺-著着zhe 個gè 死人，這.不警察剛到。 - A dead person is lying on the road, and the police has just arrived.
2. n. police officer
便衣警察 - plainclothes police officer
3. usage. Whilst 警察 usually refers to the police and police officers outside mainland China, the equivalent institution in mainland China is officially known as 公安, literally, "public security".
4. v. (literary) to be vigilant; to be alert; to watch out
5. v. (literary) to examine oneself critically; to examine one's thoughts and conduct
6. v. (literary) to supervise; to monitor