This is the 519th most frequent Estonian word.
politsei
"Politsei" means "police" in English.
Here, 'politsei' refers to the police force as an institution.
Politsei patrullib tänavatel kogu öö.
The police patrol the streets all night.
Here, 'politseil' is in the adessive case, representing possession or people responsible for action.
Politseil oli kiire reageerida hädakõnele.
The police had to respond quickly to the emergency call.
In this sentence, 'politseisse' is the illative case of 'politsei', meaning 'to the police'.