The Collaborative International Dictionary of English v.0.48:

Steadily \Stead"i*ly\ (-[i^]*l[y^]), adv.
   In a steady manner.
   [1913 Webster]

WordNet (r) 3.0 (2006):

steadily
    adv 1: at a steady rate or pace; "his interest eroded steadily"
    2: in a steady manner; "he could still walk steadily" [syn:
       steadily, steady] [ant: falteringly, uncertainly,
       unsteadily]

Moby Thesaurus II by Grady Ward, 1.0:

141 Moby Thesaurus words for "steadily":
   ad infinitum, always, at all times, at every turn,
   at regular intervals, at stated times, bec et ongles, bona fide,
   calmly, ceaselessly, committedly, composedly, conservatively,
   consistently, constantly, continually, coolly, daily,
   daily and hourly, day after day, day and night, decidedly,
   decisively, determinedly, devotedly, dispassionately, earnestly,
   endlessly, equably, eternally, evenly, ever, ever and anon,
   everlastingly, every day, every hour, every moment, every so often,
   faithfully, firmly, fixedly, hammer and tongs, heart and soul,
   hour after hour, hourly, impassively, imperturbably,
   in all seriousness, in balance, in earnest, in good earnest,
   in good faith, in moderation, in perpetuity, in reason,
   incessantly, indestructibly, inexcitably, infinitely, inflexibly,
   inirritably, interminably, intermittently, invariably, judiciously,
   levelheadedly, like a bulldog, like a leech, like clockwork,
   loyally, methodically, moderately, month after month,
   never otherwise, never-endingly, night and day, obstinately,
   on and on, orderly, perdurably, perennially, permanently,
   perpetually, perseveringly, persistently, placidly, prudently,
   punctually, purposefully, quietly, rapidly, regularly,
   relentlessly, resolutely, resolvedly, responsibly, restrainedly,
   right along, serenely, seriously, sincerely, singlemindedly,
   soberly, soothingly, staunchly, steadfastly, stodgily, stoically,
   stolidly, stuffily, subduedly, sustainedly, systematically,
   temperately, tenaciously, time without end, tooth and nail,
   tranquilly, unceasingly, unendingly, uniformly, unintermittently,
   uninterruptedly, unswervingly, unvaryingly, unyieldingly,
   wholeheartedly, with a will, with constancy, with good faith,
   with total dedication, within bounds, within compass,
   within reason, without cease, without end, without exception,
   without letup, without stopping, world without end,
   year after year