Incorrect - the word is actually Greek in origin and goes back quite a ways before WW2

hol·o·caust /ˈhäləˌkôst,ˈhōləˌkôst,ˈhäləˌkäst,ˈhōləˌkäst/ noun 1. destruction or slaughter on a mass scale, especially caused by fire or nuclear war. “a nuclear holocaust”