Learn Polish: Potrzebuję nowego paska.

The verb potrzebować (to need) is a very common verb in Polish that always forces its object into the Genitive case. Because of this, "a new belt" changes from the basic nominative form nowy pasek to the genitive nowego paska.

The dictionary word for belt is "pasek". Why does it change to "paska" and not "paseka"?

This happens because of the "fleeting e" rule in Polish. Many nouns ending in -ek drop the letter e when you add a case ending. So, pasek loses its e and becomes paska. You will also see this in words like pies (dog) becoming psa.

Because "pasek" is a masculine inanimate noun, shouldn't it take an "-u" ending in the Genitive case?

Masculine inanimate nouns in the Genitive singular can end in either -u or -a. While there is no perfect rule to know which one to use, small everyday objects and tools often take the -a ending. You just have to memorize that pasek becomes paska, not pasku.

What is the dictionary form of "potrzebuję" and why does it look so different?