Related Clues:

• Once-in-a-lifetime
• Like hens' teeth, so to speak
• Like a 1909-S VDB penny
• Far-reaching
• Chophouse order
• Measureless
• In short supply
• Not well done
• Seemingly boundless
• Still mooing, so to speak
• Really big
• Wide
• Medium-___
• Coin grade
• Like a condor