Twinkle means to shine with a flickering, unsteady light that seems to dance or pulse. Stars twinkle in the night sky because their light passes through Earth's moving atmosphere, making them appear to blink on and off rapidly. Christmas lights often twinkle by switching between bright and dim, creating a sparkling effect.

The word captures something magical about light that doesn't shine steadily. A distant city's lights might twinkle on the horizon. Dewdrops twinkle in morning sunlight as you move past them. When someone's eyes twinkle, they're bright with happiness or mischief, as if tiny lights are dancing in them.

Twinkle can also describe something happening very quickly, like in a twinkle or in the twinkling of an eye, meaning in just an instant. Before you could even blink, it has already happened.

The word feels gentle and playful, which is why it appears in lullabies and children's songs. A twinkle (as a noun) is that brief flash of light itself: the twinkle of a firefly, or the twinkle of sunlight on water.