This is the 2558th most frequent Polish word.
prus
The Polish word "prus" refers to a member of the ancient Baltic tribe called the Prussians.
Here, 'Prus' is used as a proper noun, referring to Bolesław Prus, a renowned Polish author.
Prus był znanym polskim pisarzem.
Prus was a famous Polish writer.
In this context, 'prus' refers to a species of cockroach commonly named this way in Polish colloquial language.
Na ścianie widzimy prusa - to popularne imię dla karalucha.
On the wall, we see a prus - it's a common name for a cockroach.
Here, 'Prusowie' (derived from 'Prus') refers to the historical Baltic tribe, the Prussians.