daydream
day-dream
verb
To indulge in pleasant thoughts, becoming distracted from one's surroundings.
"He would often daydream during boring lectures."
noun
A sequence of pleasant thoughts distracting one from current reality.
"She was lost in a daydream about her holiday."
Thesaurus
Synonyms: stargaze, woolgather, dream, oneirism, air castle, castle in Spain, reverie, castle in the air, revery, daydreaming, moon