someone who has murdered a lot of people 大规模杀手〔指杀害多人的凶手〕
Examples from the Corpus
mass murderer• Burt an the Yurt-man, a mass murderer and chicken-farm burner.• The art of a mass murderer.• But at this moment Kate could not have cared less if he was a mass murderer.• That year, Esquire magazine sent contributing editor Philip Caputo to Stockton to discover what might have motivated the mass murderer.