This is the 12843rd most frequent Polish word.
nudę
Boredom.
Here, 'nuda' is used as a noun to describe the concept of 'boredom'.
Czasami nuda jest nieunikniona, gdy nie mamy nic do roboty.
Sometimes boredom is inevitable when we have nothing to do.
In this sentence, 'nudy' is used in the genitive case, referring to the context of dealing with boredom.
Musisz znaleźć sposób na zwalczenie nudy w czasie deszczowych dni.
You need to find a way to combat boredom during rainy days.
Here, 'nudzie' is the dative form of 'nuda', used to indicate the indirect object 'boredom' being affected.