Eradication is the complete getting rid of something so that none of it is left. People use it most for diseases, pests, and big social problems: the eradication of smallpox, of malaria in one area, of corruption. It is a heavy, formal noun. You would not say it about wiping a board or finishing the last biscuit. The picture behind it is pulling a plant up by the root, so it cannot grow back. That is why speakers reach for it when they mean “not just reduced — gone.” In news and government talk it often names a goal more than a finished fact: a plan for eradication, a campaign of eradication. Though actually, outside a few famous cases, true eradication is rare; more often the word is doing hopeful or political work.