undeniably

vastaansanomattomasti In an undeniable manner, or to an undeniable extent.
1852 April, w:Edward Bulwer-Lytton, 1st Baron Lytton|Edward Bulwer-Lytton, My Novel; or, Varieties in English Life, Book X, Chapter III, in Harpers New Monthly Magazine'', Harper & Brothers, Volume IV, Number XXIII, http://books.google.com/books?id=ufAvAAAAMAAJ&pg=PA678&dq=undeniably page 678:

(..); and gaunt though his figure, and far from elegant though his dressing-robe, there was that about him which spoke undeniably of the grand seigneur—(..)

The third movie was undeniably the best.

No one can deny that the third movie was the best.