Where does “шлифер” come from?

шлифер (Serbo-Croatian) comes from German schlüpfen, from Middle High German slüpfen, from Old High German slupfen, from Proto-Germanic slupjaną.

Definitions

Step	Language	Word	Meaning
1	German	schlüpfen	to slip; to hatch
2	Middle High German	slüpfen	—
3	Old High German	slupfen	—
4	Proto-Germanic	slupjaną	—

шлифер — Etymology, Origin & Word History | Etymology Explorer