1. Impossible to achieve
   - unachievable, unattainable, undoable, unrealizable

See also: impossible

• Richard Phillips Feynman
• Richard Rodgers
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• Richard Starkey
• Richard Strauss
• Richard the Lion-Hearted
• Richard the Lionheart
• Richard Trevithick
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• Richards
• Richardson
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• Richardson's geranium
• Richea
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• Richelieu
• riches
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• richly