Cilia \Cil"i*a\, n. pl. Cilium, the sing., is rarely used. [L.
   cilium eyelid.]
   1. (Anat.) The eyelashes.
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   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.
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   3. (Bot.) Hairlike processes, commonly marginal and forming a
      fringe like the eyelash.
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   4. (Zool.) Small, vibratory, swimming organs, somewhat
      resembling true cilia, as those of Ctenophora.
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