Glow means to shine with a soft, steady light that seems to come from within. A firefly glows in the darkness, and the embers of a campfire glow orange long after the flames have died down. Unlike a harsh glare or sudden flash, a glow is gentle and continuous, like the warm light of a jack-o-lantern on Halloween night.

Things that glow often give off their own light rather than just reflecting it. Your phone screen glows when you turn it on in a dark room. Some deep-sea creatures glow with bioluminescence, creating their own light in the ocean's darkness. Exit signs in theaters glow so people can find their way out safely.

As a noun, a glow is that soft light itself: the glow of a night-light in the hallway, or the glow of embers in a fireplace.

The word also describes how people look when they're healthy, happy, or excited. Someone might have a healthy glow in their cheeks after playing outside, or glow with pride when receiving an award. A bride might glow on her wedding day, radiating happiness. When you say someone is glowing, you mean they look particularly vibrant and alive, as if lit up from the inside by their emotions or good health.