re·doubt·a·ble 
(rĭ-doutə-bəl)
(rĭ-doutə-bəl)adj.
1. Arousing fear or awe; formidable.
2. Worthy of respect or honor.
[Middle English redoubtabel, from Old French redoutable, from redouter, to dread : re-, re- + douter, to doubt, fear; see DOUBT.]
re·doubta·bly adv.