The Collaborative International Dictionary of English v.0.48:

Relatively \Rel"a*tive*ly\, adv.
   In a relative manner; in relation or respect to something
   else; not absolutely.
   [1913 Webster]

         Consider the absolute affections of any being as it is
         in itself, before you consider it relatively. --I.
                                                  Watts.
   [1913 Webster]

WordNet (r) 3.0 (2006):

relatively
    adv 1: in a relative manner; by comparison to something else;
           "the situation is relatively calm now" [syn:
           relatively, comparatively]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "relatively":
   after a fashion, appositely, appreciably, at any rate, at best,
   at least, at most, at the least, at the most, at the outside,
   at worst, comparably, comparatively, detectably, fairly, germanely,
   in a manner, in a way, in part, in some measure, incompletely,
   leastwise, merely, mildly, moderately, modestly, more or less,
   not absolutely, not comprehensively, not exhaustively, only, part,
   partially, partly, pertinently, pro tanto, proportionately, purely,
   rather, relevantly, simply, so far, somewhat, thus far,
   to a degree, to an extent, to some degree, to some extent,
   tolerably, visibly