The phrase "end the world" is a dramatic way to describe a catastrophic event that would permanently alter life as we know it. Synonyms for this phrase might include "apocalypse," "doomsday," "the end times," or "the end of days." Each of these terms suggests a sense of finality and absolute destruction, with little hope for survival or recovery. Other synonyms might include "cataclysm," "disaster," "Armageddon," or "judgment day." Regardless of the specific term used, these synonyms all convey the idea of an existential threat that would change the course of human history forever.