daydream
Definitions
A series of pleasant thoughts that distract one's attention from the present.
To indulge in aimless or fanciful thinking while awake.
Examples
I often daydream about traveling to exotic locations when I am stuck in boring meetings.
She was lost in a daydream, staring blankly out the window at the passing clouds.
It is easy to daydream during a long lecture, but you might miss important information.