cilia (n.)

"the eyelashes, hairs which grow from the margins of the eyelid," 1715, from Latin cilia, plural of cilium "eyelid, eyelash," perhaps related to celare "to cover, hide," from PIE root *kel- (1) "to cover, conceal, save," but words for this part of the face can be tricky (see brow). Later extended to one of the minute hair-like processes projecting from a cell or organism (1835). It sometimes is pluralized in English, which is an error. Related: Ciliary; ciliate.