Up to 1.5 million people were killed, and the word to describe it didn't exist yet
Beginning in 1915, the Ottoman government carried out the mass killing and deportation of its Armenian population, leaving an estimated 600,000 to 1.5 million dead. The scale of the atrocity directly influenced lawyer Raphael Lemkin's coining of the word 'genocide' decades later, in 1944.
— Wikipedia contributors, Armenian genocide — Encyclopedia entry