Is it farther or further?
Old English flean "to skin" (strong verb, past tense flog, past participle flagen), from Proto-Germanic *flakhanan (cf. Middle Dutch vlaen, Old High German flahan, Old Norse fla), from PIE root *plak- (2) "to hit" (cf. Greek plessein "to strike," Lithuanian plešiu "to tear;" see plague (n.)). Related: Flayed; flaying.