cilium

plural cilia

1. biologyA short microscopic hairlike organelle projecting from a eukaryotic cell (such as a unicellular organism or one cell of a multicelled organism) which serve either for propulsion by causing currents in the surrounding fluid or as sensors.

   The clockwise beating of cilia results in a net flow of extraembryonic fluid leftwards […]

   2006, Manfred Schliwa, Molecular Motors, page 359

   1 more example

   It is the deeper parts of such cells which give rise to delicate muscular fibres or networks of fibres, while the superficially placed body of the cell myoblast), the part which produces the above, performs other functions, and usually bears a cilium.

   1892, Carl Friedrich Wilhelm Claus, edited by F. G. Heathcote, Elementary Text-book of Zoology

2. biologyOne of the fine hairs along an insect's wing.
3. biologyOne of the hairs or similar protrusions along the margin of an organ.
4. anatomyAn eyelash.