cilia /sil″ē·ə/ sing. cilium [L, eyelids or eyelashes] , 1. the eyelids or eyelashes. 2. small, hairlike processes projecting from epithelial cells on the outer surfaces of some tissues, aiding metabolism by producing motion, eddies, or current in a fluid. In the lung, cilia wave mucus, pus, and dust upward.
