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third eyelid Line breaks: third eye¦lid

Definition of third eyelid in English:


Informal term for nictitating membrane.
Example sentences
  • Crocodilians' eyes are immobile spheres covered by three eyelids: the third eyelid, the nictitating membrane, is transparent, but protects the eye from water.
  • Eversion of the nictitating membrane is a condition in which the third eyelid protrudes.
  • These membranes, essentially a third eyelid, can cover the exposed portion of the eye, since, as in all sharks, the upper and lower eyelids of catsharks cannot completely cover the eyeball.
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