1. Something desirable but not likely to happen

Encyclopedia: Pie in the sky

• unsold
• unsolder
• unsoldierly
• unsolicited
• unsoluble
• unsolvability
• unsolvable
• unsolved
• unsophisticated
• unsorted
• unsought
• unsound
• unsoundable
• unsounded
• unsoundness
• unsourced
• unsoured
• unsown
• unspaced
• unsparing
• unsparingly
• unspeakable
• unspeakably
• unspecialised
• unspecialized