1. relating to or designating a membrane (nictitating membrane) that can be drawn across the eye, especially in birds, reptiles, and some mammals
Usage: technical/anatomical; often used in the phrase 'nictitant membrane' or 'nictitating membrane'

Examples

• The nictitant membrane in birds helps protect the eye during flight.
• Reptiles possess a nictitant membrane that slides across the eye horizontally.
• The nictitant fold is a vestigial structure in humans.
• Many aquatic animals have a well-developed nictitant membrane.
• The nictitant apparatus is controlled by specialized muscles in the eye socket.