filch (v.)youdaoicibaDictYouDict[filch 词源字典]
"steal," especially in a small, sly way, 1560s, slang, perhaps from c. 1300 filchen "to snatch, take as booty," which is of unknown origin. Liberman says filch probably is from German filzen "comb through." Related: Filched; filching.[filch etymology, filch origin, 英语词源]