From the present participle nictitans nictitantis of the verb nictito , frequentive of nicto because it indicates the repeated action of blinking . It is said of a membrane of the eye of some animals that zoologists also call the third eyelid (palpebra tertia), a transparent or translucent cloth with protective function. Birds of prey such as the eagle or the falcon thus protect their eyes when they launch at 200 or 300 km / h to hunt.
