Cilia: The fine hairlike projections from certain cells such as those in the respiratory tract that sweep in unison and help to sweep away fluids and particles. Some single-celled organisms use the rhythmical motion of cilia for locomotion.
Cilia is the plural of cilium, a Latin word referring to the edge of the eyelid and, much later, to the eyelashes. Cilia came to be known fine hairlike projections from cells.
