‖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 ]