An incinerator is a machine — often a whole building with a tall chimney — built to burn things until they are gone. The point is not to cook or to keep a room warm. The point is to destroy. Cities use big ones for household rubbish; hospitals use smaller, hotter ones for things that must not be thrown out with ordinary waste, like used dressings. The fire inside is far hotter than a kitchen stove, and the smoke is meant to be cleaned before it leaves. People also say “the incinerator” for the plant that does this work, not only the metal box itself. It is a technical word. In everyday talk someone might just say they are going to “burn the rubbish,” but an incinerator is the special machine for doing that job safely and on purpose.