Meaning

noun an act of mass destruction and loss of life (especially in war or by fire)

noun the mass murder of Jews under the German Nazi regime from 1941 until 1945

originThe noun is derived from Middle English holocaust (“burnt offering”) [and other forms], from Anglo-Norman holocauste, Old French holocauste, olocauste (modern French holocaust), from Late Latin holocaustum, from Ancient Greek ὁλόκαυστον (holókauston), the neuter form of ὁλόκαυστος (holókaustos, “wholly burnt”), from ὅλος (hólos, “entire, whole”) (ultimately from Proto-Indo-European *solh₂-…

Etymology from Wiktionary, CC BY-SA 3.0