Related Clues:

• 'Cool, dude!'
• "Sweet!"
• Cooler than cool
• Swell, '90s-style
• "Awesome!"
• X-ray dose
• Physicist's unit
• Gnarly
• "Groovy!"
• 'Gnarly!'
• "Gnarly!"
• X-ray unit
• Far out!
• More than cool
• 90's kids' catchword