This is the 1897th most frequent French word.
policier
"Policier" means "police officer" in English.
Here, 'policier' is used as a noun, meaning 'police officer', referring to an individual in law enforcement.
Le policier a arrêté le voleur.
The police officer arrested the thief.
In this context, 'policier' is an adjective modifying 'roman' (novel), describing it as related to crime or detective stories.
Ce roman policier est très captivant.
This detective novel is very captivating.
Here, 'policiers' is a plural adjective describing 'films' (movies), indicating their genre is related to crime or law enforcement.