A ciliated protozoan is a single-celled organism that moves by using hair-like structures called cilia. These organisms play an important role in aquatic ecosystems as they are responsible for consuming bacteria and other small organisms. There are various synonyms for ciliated protozoans, including ciliates, infusoria, and protozoa. Ciliates are referred to as such due to their cilia, while infusoria is a term used to describe protozoans that are commonly found in infusions of organic matter. Protozoa, on the other hand, is a more general term used to describe all single-celled eukaryotic organisms that are not classified as plants, fungi, or animals.