This is the 14470th most frequent Polish word.
przestać
"Przestać" means "to stop" or "to cease."
The word 'przestać' is used to indicate stopping a continuous action, which in this case is eating sweets.
Musisz przestać jeść słodycze.
You must stop eating sweets.
Here, 'przestać' reflects the inability to cease a mental activity, thinking.
Nie mogę przestać myśleć o wakacjach.
I can't stop thinking about the vacation.
In this sentence, 'przestać' conveys the cessation of a belief or trust in something.