Closes and opens the eyes quickly (verb), or those quick eye closures (noun); also means to shine intermittently or hesitate.
Possibly from Low German 'blenken' or onomatopoeia mimicking the action. Used since Middle English to describe the eye movement and the brief moments of darkness that follow.
You blink about 15,000 times a day without thinking, and your brain actually deletes those blink moments from your visual memory—so you never notice the constant darkness!
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