1. Impossible to achieve
   - unachievable, unattainable, unrealizable, unrealisable [Brit]

See also: impossible

Encyclopedia: Undoable

• soundman
• soundness
• soundproof
• soundtrack
• soup
• soup bowl
• soup du jour
• soup kitchen
• soup ladle
• soup plate
• soup up
• soup-strainer
• soupfin
• soupfin shark
• soupiness
• soupspoon
• soupy
• soupçon
• sour
• sour bread
• sour cherry
• sour cherry tree
• sour cream
• sour dock
• sour fig