1. Inspiring fear
   "a tougher and more redoubtable adversary than the heel-clicking, jackbooted fanatic"
   - formidable, unnerving, doubtable [archaic] 
2. Worthy of respect or honour
   "born of a redoubtable family"

See also: alarming, reputable

• dura mater
• durability
• durable
• durable goods
• durable press
• durables
• durably
• Durabolin
• dural
• Duralumin
• duramen
• durance
• Durango
• Durant
• Durante
• duration
• durative
• durative aspect
• Durazzo
• Durban
• durbar
• Durer
• duress
• Durex
• Durga