Definition of cilium in English:

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Pronunciation: /ˈsɪlɪəm/

noun (usually in plural cilia /ˈsɪlɪə/)

1 Biology A short microscopic hair-like vibrating structure found in large numbers on the surface of certain cells, either causing currents in the surrounding fluid, or, in some protozoans and other small organisms, providing propulsion.
Example sentences
  • Some single-celled organisms called protists do in fact use cilia on their cell surface to swim through water.
  • Our respiratory systems are lined with millions of tiny cilia that clean all kinds of irritants - germs, dust, mucus - out of our bodies.
  • As the cilia whip around clockwise, they circulate the fluids.
2 Anatomy An eyelash.
Example sentences
  • Ectopic cilia are particularly irritating and likely to cause corneal ulcers.
  • Normally the eyelashes (or cilia) grow from follicles in the eyelid.


Early 18th century (in the sense 'eyelash'): from Latin.

Words that rhyme with cilium

beryllium, psyllium, trillium

For editors and proofreaders

Line breaks: cil¦ium

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