cil·​i·​um | \ ˈsi-lē-əm How to pronounce cilium (audio) \
plural cilia\ ˈsi-​lē-​ə How to pronounce cilium (audio) \

Definition of cilium

1 : a minute short hairlike process often forming part of a fringe especially : one on a cell that is capable of lashing movement and serves especially in free unicellular organisms to produce locomotion or in higher forms a current of fluid
2 : eyelash

Examples of cilium in a Sentence

Recent Examples on the Web Cilia are found throughout our bodies, but only a small number of kinds of cells have more than one cilium apiece. Caroline Delbert, Popular Mechanics, 30 Dec. 2019 When those cilia become paralyzed, they are rendered unable to do their job protecting the lungs, and this increases your risk of infection, like pneumonia. Maggie O'neill,, 12 Sep. 2019 Among their design concerns were methods for nurturing cilium and for recycling sweat. Guy Trebay, New York Times, 26 Sep. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cilium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of cilium

1794, in the meaning defined at sense 1

History and Etymology for cilium

New Latin, from Latin, eyelid; akin to Latin celare to conceal — more at hell

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Cite this Entry

“Cilium.” Dictionary, Merriam-Webster, Accessed 29 Jul. 2021.

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More Definitions for cilium


cil·​i·​um | \ ˈsi-lē-əm How to pronounce cilium (audio) \
plural cilia\ ˈsi-​lē-​ə \

Kids Definition of cilium

: a tiny hairlike structure on the surface of some cells


cil·​i·​um | \ ˈsil-ē-əm How to pronounce cilium (audio) \
plural cilia\ -​ē-​ə How to pronounce cilium (audio) \

Medical Definition of cilium

1 : eyelash
2 : a minute, short, hairlike process that projects from the surface of most eukaryotic cells, is composed chiefly of microtubules, in unicellular organisms functions chiefly in locomotion, and in higher forms serves especially in the movement of fluids and particles (as the passage of mucus and dust from the lungs) and in sensory reception — see ciliopathy

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