A “cilium” is a microscopic, hair-like structure that extends from the surface of many eukaryotic cells. Cilia are typically involved in movement or the movement of substances along the cell surface. They can either be motile, helping in locomotion or in the movement of fluids, or non-motile, serving as sensory organelles. Cilia are found in various organisms, including protozoa, algae, and certain animal cells, most notably in the respiratory tract where they help to clear mucus and debris. The term “cilia” is the plural form of “cilium.”
