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.(Zool.) Small, vibratory, swimming organs, somewhat resembling true cilia, as those of Ctenophora.