a small pale light, especially one that shines for a short time [= glimmer]
They saw a sudden gleam of light.
the brightness of something that shines [= glint]
the gleam of gold and diamonds
an emotion or expression that appears for a moment on someone's face
She saw a gleam of amusement in his eyes.
Rose looked at me with a furious gleam in her eyes.
used to say that something is being planned or thought about, but does not yet exist:
In those days, CD-ROMs were still just a gleam in the eye of some young engineer.