An eyelid is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. "Palpebral" means relating to the eyelids. Its key function is to regularly spread the tears and other secretions on the eye surface to keep it moist, since the cornea must be continuously moist. They keep the eyes from drying out when asleep. Moreover, the blink reflex protects the eye from foreign bodies. A set of specialized hairs known as lashes grow from the upper and lower eyelid margins to further protect the eye from dust and debris.

पक्ष्म शरीरस्य किञ्चन अङ्गम् अस्ति । आङ्ग्लभाषायां पक्ष्म Eyelid इति उच्यते । बाह्येभ्यः अवरोधेभ्यः नेत्रस्य रक्षणं करोति पक्ष्म ।