blink
n. countablen. the quick act of closing and opening your eyes. It can also be a short flash of light from a lamp or a screen.
n. a reflex act of closing and opening the eyelids rapidly; by extension, a brief flash of light or a momentary glimmer.
She gave a quick blink when the bright light turned on.
The lighthouse signal was just a tiny blink on the dark horizon, but it guided the sailors home.
In the blink of an eye, the magician swapped the cards, leaving the audience wondering how such a physical impossibility had occurred right before them.
From Middle English blynken, blenken, from Old English blincan (suggested by causative verb blenċan (“to deceive”); > English blench), from Proto-Germanic blinkaną, a variant of *blīkaną (“to gleam, shine”). Cognate with Dutch blinken (“to glitter, shine”), German blinken (“to flash, blink”), Danish blinke (“to flash, twinkle, wink, blink”), Swedish blinka (“to flash, blink, twinkle, wink, blink”). Related to blank, blick, blike, bleak.
Often used in the idiomatic phrase 'in the blink of an eye' to mean very quickly.