nictitating membrane

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Related to Semilunar fold: semilunar fold of conjunctiva

nic·ti·tat·ing membrane

 (nĭk′tĭ-tā′tĭng)
n.
A transparent inner eyelid in many vertebrates that closes to protect and moisten the eye. Also called third eyelid.

nictitating membrane

(ˈnɪktɪˌteɪtɪŋ)
n
(Zoology) (in reptiles, birds, and some mammals) a thin fold of skin beneath the eyelid that can be drawn across the eye. Also called: third eyelid or haw

nic′titating mem′brane


n.
a thin membrane, present in many animals, that can be drawn across the eyeball for protection.
[1705–15]

nic·ti·tat·ing membrane

(nĭk′tĭ-tā′tĭng)
A transparent inner eyelid in birds, reptiles, amphibians, and some mammals that protects and moistens the eye without blocking vision.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.nictitating membrane - a protective fold of skin in the eyes of reptiles and birds and some mammalsnictitating membrane - a protective fold of skin in the eyes of reptiles and birds and some mammals
eye, oculus, optic - the organ of sight
protective fold - a flap of tissue that protects what it covers
haw - the nictitating membrane of a horse