This is the 11224th most frequent Polish word.
grzechu
"Grzechu" means "sin" (genitive case) in English.
Here, 'grzechu' is used in its literal sense to describe a characteristic of a location or its history.
Legenda głosi, że istniało miejsce pełne grzechu i pokusy.
Legend has it there was a place full of sin and temptation.
In this sentence, 'grzechu' refers to a state or emotion leading to moral wrongdoing.
Nie podejmuj decyzji w przypływie grzechu.
Do not make decisions in the heat of sin.
Here, 'grzechu' is used metaphorically to emphasize the value of an action or thing.