An Etymological Dictionary of the German Language/Funke
Funke, m., from the equiv. MidHG. (not a classical form) vunke, m., OHG. funcho, m., ‘spark’; comp. Du. vonk, ‘spark,’ MidLG. and MidE. funke, ‘small fire, spark,’ E. funk, ‘round wood, steam, stink.’ Classical MidHG. has vanke, m. It is uncertain whether Goth. fôn (gen. fŭnins), ‘fire,’ is allied; it is more probable that Sans. pâjas, ‘splendour, gleam of light,’ is primit. cognate.