From Middle English *libben (suggested by libbyng (“gelding”), lybbere (“gelder”)), related to Dutch lubben (“to castrate, emasculate”), Dutch libbe (“a steer”), lubbert (“a eunuch”). Further relation uncertain. Possibly related to Old English *lybban (“to doctor”), from Proto-West Germanic *lubbjan; or perhaps related to Old English lappa, læppa (“lappet, piece, section, lobe, portion, district”). More at lop.
Meanings
(Northern-England, Scotland, UK, dialectal, transitive) To geld; castrate; emasculate (usually said of animals).