This is the 16593rd most frequent Polish word.
wolontariuszom
"Wolontariuszom" means "to the volunteers" in English.
Here, 'wolontariuszom' is in the dative plural form and used as the indirect object of the verb 'dziękowaliśmy' indicating to whom we directed our thanks.
Dziękowaliśmy wolontariuszom za ich poświęcenie.
We thanked the volunteers for their commitment.
In this sentence, 'wolontariuszom' is again the dative plural form and shows to whom the assistance was provided, being the indirect object of the verb 'pomogliśmy'.
Pomogliśmy wolontariuszom w organizacji wydarzenia.
We helped the volunteers in organizing the event.
Here, 'wolontariuszom' is also in dative plural form used with the verb 'zależy' indicating to whom this concern is attributed, forming a subject-like role with the focus on care or interest.