Llyn y Fan Fach Llyn y Fan Fach Llyn y Fan Fach (Welsh meaning "Lake of the small hill") is a lake of approximately 10 hectares on the northern margin of the Black Mountain in Carmarthenshire, South Wales and lying within the Brecon Beacons National Park. The lake lies at an altitude of approximately , immediately to the north of the ridge of the Carmarthen Fans. It is the smaller of two lakes within this mountain massif: the slightly larger Llyn y Fan Fawr is about to the east. The lake is overlooked by several prominent mountain peaks, especially Picws Du and Waun Lefrith.
Pen-y-ghent language, exactly as in today's Welsh, "Pen" meant 'top' or 'head', and "y" is most likely the definite article ("the"), exactly as in Modern Welsh "y". These elements are common in placenames throughout the island, and especially in Wales (compare Penyberth 'end of the hedge/copse', or Penyffordd 'head of the road/way', etc.). The element "ghent" is more obscure, however: it could be taken to be 'edge' or 'border'. The name "Pen-y-ghent" could therefore mean 'Hill on the border' (compare Kent). Alternatively, "ghent" could mean 'wind' or 'winds' – from the closest Welsh transliteration, "gwynt" ('wind'). Thus it might mean simply