The Collaborative International Dictionary of English v.0.48:

Merely \Mere"ly\, adv.
   1. Purely; unmixedly; absolutely.
      [1913 Webster]

            Ulysses was to force forth his access,
            Though merely naked.                  --Chapman.
      [1913 Webster]

   2. Not otherwise than; simply; barely; only.
      [1913 Webster]

            Prize not your life for other ends
            Than merely to oblige your friends.   --Swift.
      [1913 Webster]

   Syn: Solely; simply; purely; barely; scarcely.
        [1913 Webster]

WordNet (r) 3.0 (2006):

merely
    adv 1: and nothing more; "I was merely asking"; "it is simply a
           matter of time"; "just a scratch"; "he was only a child";
           "hopes that last but a moment" [syn: merely, simply,
           just, only, but]

Moby Thesaurus II by Grady Ward, 1.0:

60 Moby Thesaurus words for "merely":
   after a fashion, alone, appreciably, at any rate, at best,
   at bottom, at least, at most, at the least, at the most,
   at the outside, at worst, barely, basically, but, comparatively,
   detectably, entirely, essentially, exclusively, fairly,
   fundamentally, in a manner, in a way, in part, in some measure,
   incompletely, integrally, irreducibly, just, leastwise, mildly,
   moderately, modestly, not comprehensively, not exhaustively, only,
   part, partially, partly, plainly, pro tanto, purely, relatively,
   scarcely, simply, simply and solely, singly, so far, solely,
   somewhat, thus far, to a degree, to some degree, tolerably,
   totally, unanalyzably, undividedly, visibly, wholly