1. (

• formidable ,
• redoubtable ,
• unnerving

) inspiring fear; "the formidable prospect of major surgery"; "a tougher and more redoubtable adversary than the heel-clicking, jackbooted fanatic"- G.H.Johnston; "something unnerving and prisonlike about high grey wall" ;

2. (

• redoubtable

) worthy of respect or honor; "born of a redoubtable family" ;