This is the 15603rd most frequent Russian word.
пригрозил
"Threatened."
The word 'пригрозил' here expresses a verbal threat to perform an action if certain conditions are not met.
Он пригрозил уйти, если переговоры не увенчаются успехом.
He threatened to leave if the negotiations were not successful.
The word 'пригрозил' in this sentence signifies a warning related to an action (calling the police) if a rule (paying the fare) is violated.
Водитель пригрозил вызвать полицию, если пассажир не оплатит проезд.
The driver threatened to call the police if the passenger does not pay the fare.
Here, 'пригрозил' is used to convey a potential consequence as a deterrent against misconduct (cheating).