spunk

1530, blend of spark + funk (obsolete, “spark”). Funk (“spark, touchwood”) is from Middle English funke, fonke (“spark”), from Old English funca (“spark”), from Proto-West Germanic funkō, from Proto-Germanic funkô (“spark”), from Proto-Indo-European (s)peng- (“to shine”), and is akin to Middle Low German funke, fanke (“spark”), Middle Dutch vonke (“spark”), Old High German funcho, funko (“spark”), German Funke (“spark”).