This is the 4862nd most frequent Polish word.
oszust
"Cheat" or "fraud."
It refers to a person who commits unjust actions by deceiving others.
Oszust ukradł portfel mojego znajomego.
The fraudster stole my friend's wallet.
Here, it indicates someone using deception to profit from others.
Ten sprzedawca to oszust, bo sprzedaje podrobione towary.
This vendor is a fraud because they sell counterfeit products.
In this case, it generalizes individuals who use deceitful methods to persuade or manipulate others.