What is "pantperthog"

Pantperthog is a hamlet in southern Gwynedd in Wales, 2 miles north of Machynlleth and 14 miles southeast of Dolgellau. Nearby is the former Llwyngwern quarry, which is now the Centre for Alternative Technology. The Afon Dulas, which here forms the border between Gwynedd and Powys, runs past the hamlet.