wälsch (wälisch (Middle High German) comes from Old High German walahisc, from Proto-Germanic *walhisk, from Proto-Germanic walhiskaz, from Proto-Germanic walhaz, from Latin Volcae, from Proto-Celtic wolkos, from Proto-Indo-European welg- — wet, damp.
Ancestry of “wälsch (wälisch”, step by step
wälsch (wälisch traces back through 3 separate lines of ancestry.