This is the 17817th most frequent Polish word.
zwycięzcą
Winner.
Here, 'zwycięzcą' is used as a noun in the instrumental case, illustrating someone's achievement as winning.
Janek został zwycięzcą maratonu.
Janek became the winner of the marathon.
In this sentence, 'zwycięzcę' is used as a noun in the accusative case, indicating the direct object inquiring about the person who won.
Czy znasz zwycięzcę konkursu?
Do you know the winner of the contest?
Here, 'zwycięzcą' functions as a noun in the instrumental case as part of a predicate, describing attributes associated with the winner.