The Collaborative International Dictionary of English v.0.48:

Inevitably \In*ev"i*ta*bly\, adv.
   Without possibility of escape or evasion; unavoidably;
   certainly.
   [1913 Webster]

         Inevitably thou shalt die.               --Milton.
   [1913 Webster]

         How inevitably does immoderate laughter end in a sigh!
                                                  --South.
   [1913 Webster]

WordNet (r) 3.0 (2006):

inevitably
    adv 1: in such a manner as could not be otherwise; "it is
           necessarily so"; "we must needs by objective" [syn:
           inevitably, necessarily, of necessity, needs]
    2: by necessity; "the situation slid inescapably toward disaster
       " [syn: inescapably, ineluctably, inevitably,
       unavoidably]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "inevitably":
   accordingly, and so, as a consequence, as a result, certainly,
   consequently, fatefully, finally, inconsequence, indefeasibly,
   ineluctably, inescapably, inevasibly, inexorably, inflexibly,
   irrevocably, it follows that, naturally, naturellement,
   necessarily, of course, of necessity, perforce, relentlessly,
   surely, therefore, unavoidably, uncontrollably, unpreventably,
   unyieldingly