A glimmer is a faint, unsteady light that shines weakly or appears and disappears. You might see a glimmer of moonlight on a lake at night, flickering as ripples move across the water. A candle across a dark room casts a glimmer, not bright enough to read by but enough to show where something is.

The word also describes a small sign or trace of something, especially hope or possibility. When your team is losing badly but scores a goal, there's a glimmer of hope that you might catch up. If you're stuck on a difficult puzzle and suddenly notice a clue, you might feel a glimmer of understanding starting to form. A glimmer of an idea means the beginning of a thought, not yet fully formed.

Glimmer works as a verb too. Stars glimmer in the night sky. A distant lighthouse glimmers through the fog. Unlike a steady beam or a bright flash, a glimmer is gentle and uncertain, like light that's trying hard to reach you but can barely make it through.