資料來源 : Webster's Revised Unabridged Dictionary (1913)

Undeniably \Un`de*ni"a*bly\, adv.
   In an undeniable manner.

資料來源 : WordNet®

undeniably
     adv : to an undeniable degree or in an undeniable manner; "she is
           undeniably the most gifted student in the class"