Twinkle/ˈtwɪŋkl/ Definition 1 of 5Pro Tip 1/2Constantly Changing Use 'twinkle' for lights that change brightness rapidly, like stars or reflections. The necklace seemed to twinkle under the store lights. Pro Tip 2/2Natural Phenomena 'Twinkle' often describes natural light sources, not electronic or artificial ones. Fireflies twinkle as they fly through the summer garden.