An Etymological Dictionary of the German Language/Annotated/Feuer
Feuer, neuter, ‘fire, ardour, passion,’ from the equivalent Middle High German viur, Old High German and Old Low German fiur, older fûir, neuter; compare Dutch vuur, Anglo-Saxon fŷr (from *fûir), neuter, English fire; a word common to West Teutonic for ‘fire’; in Gothic fön (genitive funins), Old Icelandic fune, ‘fire,’ but it is doubtful whether they are cognate with High German Feuer; compare Old Icelandic (only in poetry) fúrr, masculine, and fýre, neuter, ‘fire.’ The r in all the words is a suffix, and fû (from pre-Teutonic pû) the root; compare Greek πῦρ and Æolic πύΐρ, neuter (πυρσός, ‘torch’). In Sanscrit a verbal root pû, ‘to flame, beam brightly,’ is found, whence pâvaká, ‘fire.’