\Cil"i*a\, n. pl. {Cilium}, the sing., is rarely used. [L.
cilium eyelid.]
1. (Anat.) The eyelashes.
2. (Biol.) Small, generally microscopic, vibrating appendages
   lining certain organs, as the air passages of the higher
   animals, and in the lower animals often covering also the
   whole or a part of the exterior. They are also found on
   some vegetable organisms. In the Infusoria, and many
   larval forms, they are locomotive organs.
3. (Bot.) Hairlike processes, commonly marginal and forming a
   fringe like the eyelash.
4. (Zo["o]l.) Small, vibratory, swimming organs, somewhat
   resembling true cilia, as those of Ctenophora.