Czynnemu
Czynnemu is the dative singular masculine form of the Polish adjective czynny, which means active, in operation, or engaged in action. It is used when the noun it modifies is masculine and in the dative case, forming part of a noun phrase.
For example: Dałem zadanie czynnemu pracownikowi. This translates to I gave the task to the active/engaged worker.
Czynnemu does not carry an independent lexical meaning beyond that of czynny; it is a grammatical inflection.
Etymology and morphology: czynny derives from the root czyn- meaning act or deed, with the adjectival ending