An Etymological Dictionary of the German Language/Annotated/Fahne
Fahne, feminine (masculine in Upper German), ‘banner, flag, standard, squadron,’ from Middle High German vane, van, masculine ‘flag, banner’; in this sense Old High German has the compound gundfano, masculine, since fano most frequently means ‘cloth’ (compare ougafano, ‘veil,’ halsfano, ‘neckcloth’); allied to Gothic fana, ‘cloth, stuff, rag,’ Anglo-Saxon fana and gûþfana, masculine, ‘standard, banner,’ English fane, vane, Dutch vaan, ‘flag.’ The Teutonic fanan, pre-Teutonic pano-n-, has in the wider sphere of the Aryan languages many cognates which also point to the general and older meaning, ‘stuff, cloth’; Latin pannus, ‘small piece of cloth, rag,’ Old Slovenian o-pona, ‘curtain,’ ponjava, feminine, ‘sail.’ Akin also perhaps to Greek πῆνος, neuter, ‘garment,’ πηνίον, ‘spool, spindle.’ An Aryan verbal root, pen, appears in Old Slovenian pĭną (pęti), ‘to span, hang.’ The Old Teutonic gunþfano, ‘standard,’ was adopted with the meaning ‘flag’ by Romance (compare French gonfalon, Italian gonfalone), while the simple form in Romance retained at different times the earlier and general meaning (compare Old French and Modern French fanon, ‘rag, towel, fanon (of a priest).’ —