1. Incapable of being ascended
   - unclimbable

Antonym: scalable

• Urbana
• urbane
• urbanely
• urbanisation
• urbanise
• urbanised
• urbanism
• urbanite
• urbanity
• urbanization
• urbanize
• urbanized
• urceolate
• urceole
• urchin
• Urd
• Urdu
• urea
• urea-formaldehyde resin
• urease
• Uredinales
• ureide
• uremia
• uremic
• ureter