1. Incapable of being ascended
   - unclimbable

Antonym: scalable

• tax-deductible
• tax-exempt
• tax-exempt security
• tax-free
• tax-increase
• taxability
• taxable
• Taxaceae
• Taxales
• taxation
• taxer
• taxi
• taxi dancer
• taxi fare
• taxi rank
• taxi strip
• taxicab
• Taxidea
• Taxidea taxus
• taxidermist
• taxidermy
• taxidriver
• taximan
• taximeter
• taxing