pipe dream, An unrealistic or impractical hope or plan.
dream come true, A wish or desire that has been fulfilled.
Word Origin
Language
Old English
Original word
drēam
Originally meant
joy, mirth, music
Background
The word 'dream' in Old English originally meant 'joy' or 'music', reflecting a more positive connotation. Over time, it evolved to refer to the visions and thoughts experienced during sleep.