An atomizer is a small bottle or tool that sends liquid out as a mist of very fine drops. The picture most people have is a perfume bottle: you press or squeeze, and a cloud of scent comes out. The same kind of tool sprays room fragrance or some medicines you breathe. In newer English, the heating part of an e-cigarette is also called an atomizer. The name wants to say turn it into atoms — meaning into the smallest bits — though actually the drops are still far bigger than real atoms; it is an old, loose use of atom. British spelling is often atomiser.