eyelid

eyelid
eye‧lid /ˈaɪlɪd/ noun [countable]
a piece of skin that covers your eye when it is closed:
    His eyelids began to droop (=close, because he was sleepy).
    The room spun. Her eyelids fluttered (=moved up and down quickly) and she fainted. ⇨ not bat an eyelid at bat²(2)