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

• Elijah
• Elijah Muhammad
• eliminate
• elimination
• elimination reaction
• elimination tournament
• eliminator
• Elinor Morton Hoyt Wylie
• ELINT
• Elinvar
• Eliomys
• Eliot
• ELISA
• Elisabeth Vigee-Lebrun
• Elisabethville
• Elisha Graves Otis
• elision
• elite
• elite group
• elitism
• elitist
• elixir
• elixir of life
• Elixophyllin
• Elizabeth