nictitating membrane

Noun

Synonyms: nictitating membrane third eyelid

WordNet 3.0

Noun (1)

a protective fold of skin in the eyes of reptiles and birds and some mammalsSynonyms: nictitating membrane third eyelid

Webster's Dictionary (GCIDE)

Nictitate \Nic"ti*tate\, v. i. [See Nictate.] To wink; to nictate. [1913 Webster]

Nictitating membrane (Anat.), a thin membrane, found in many animals at the inner angle, or beneath the lower lid, of the eye, and capable of being drawn across the eyeball; the third eyelid; the haw. [1913 Webster]