The Collaborative International Dictionary of English v.0.48:

Cilia \Cil"i*a\, n. pl. Cilium, the sing., is rarely used. [L.
   cilium eyelid.]
   1. (Anat.) The eyelashes.
      [1913 Webster]

   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.
      [1913 Webster]

   3. (Bot.) Hairlike processes, commonly marginal and forming a
      fringe like the eyelash.
      [1913 Webster]

   4. (Zool.) Small, vibratory, swimming organs, somewhat
      resembling true cilia, as those of Ctenophora.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cilium \Cil"i*um\, n. [L., eyelid.]
   See Cilia.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cilium
    n 1: a hairlike projection from the surface of a cell; provides
         locomotion in free-swimming unicellular organisms
    2: any of the short curved hairs that grow from the edges of the
       eyelids [syn: eyelash, lash, cilium]