frith2 (1366)[gdw]
In origin an English word meaning 'game preserve', 'enclosed park', or 'woodland', when appearing in Welsh and Cambro-Latin contexts the term seems to show an additional, more specialised, meaning, 'hill pasture': see DMLBS as well as Geiriadur Prifysgol Cymru/A Dictionary of the Welsh Language ffridd. This additional sense is arguably present in Anglo-Norman, in the citation below from RLiR 58.