Where does “młóciwać” come from?

młóciwać (Polish) comes from Polish młócić, from Proto-Slavic moltìti — to beat, to thresh.

Ancestry of “młóciwać”, step by step

Step	Language	Word	Meaning
1	Polish	młócić	to thresh; to thrash, to pommel; to play a game...
2	Proto-Slavic	moltìti	to beat, to thresh