Related Clues:

• 'Cool, dude!'
• "Peachy!"
• 'Marvy!'
• "Rad!"
• "Sweet!"
• Cooler than cool
• Swell, '90s-style
• Groovy!
• "Awesome!"
• "Outta sight!"
• X-ray dose
• Physicist's unit
• Gnarly
• "Groovy!"
• Nifty, in the '50s