The Collaborative International Dictionary of English v.0.48:

Approximately \Ap*prox"i*mate*ly\, adv.
   With approximation; so as to approximate; nearly.
   [1913 Webster]

WordNet (r) 3.0 (2006):

approximately
    adv 1: (of quantities) imprecise but fairly close to correct;
           "lasted approximately an hour"; "in just about a minute";
           "he's about 30 years old"; "I've had about all I can
           stand"; "we meet about once a month"; "some forty people
           came"; "weighs around a hundred pounds"; "roughly
           $3,000"; "holds 3 gallons, more or less"; "20 or so
           people were at the party" [syn: approximately, about,
           close to, just about, some, roughly, more or
           less, around, or so]

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "approximately":
   about, all but, all in all, almost, almost entirely, approaching,
   approximatively, around, by and large, chiefly, circa, close to,
   effectually, essentially, for practical purposes, generally,
   generally speaking, in round numbers, in the main, mainly,
   more or less, most, mostly, much, nearabout, nearly, nigh,
   on balance, on the whole, plus ou moins, practically, roughly,
   roughly speaking, roundly, say, some, substantially, virtually,
   well-nigh