third eyelid

noun

1. nictitating membrane.

third eyelid

noun

1. another name for nictitating membrane

Example Sentences

The surgery was complicated by the unique characteristics of penguins, such as a third eyelid, which protects their eyes underwater but had a tendency to close during the surgery.

From BBC

His daughter searched for information online and learned about a membrane, or third eyelid, that protects the birds’ peepers in-flight and on fishing expeditions.

From Washington Post

But the third eyelid actually plays an important role in maintaining the eye's health.

From Scientific American

A third eyelid, between the regular eyelids and the cornea, protects the globe and also has a gland at the bottom that produces extra tears.

From New York Times

The eye is provided with a nictitating membrane or third eyelid, at the base of which open the ducts of the Harderian gland.

From Project Gutenberg