The Collaborative International Dictionary of English v.0.48:

Invariable \In*va"ri*a*ble\, a. [Pref. in- not + variable: cf.
   F. invariable.]
   Not given to variation or change; unalterable; unchangeable;
   always uniform.
   [1913 Webster]

         Physical laws which are invariable.      --I. Taylor.
   -- In*va"ri*a*ble*ness, n. -- In*va"ri*a*bly, adv.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

invariably \in*va"ri*a*bly\ adv.
   Always; in every case.
   [PJC]

WordNet (r) 3.0 (2006):

invariably
    adv 1: without variation or change, in every case; "constantly
           kind and gracious"; "he always arrives on time" [syn:
           constantly, invariably, always]

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "invariably":
   abidingly, all along, all over, all the time, all the while,
   always, at all times, at every turn, changelessly, constantly,
   continually, cosmically, enduringly, ever, ever and always,
   everywhere, galactically, in every instance, inflexibly,
   internationally, lastingly, like clockwork, methodically,
   never otherwise, orderly, permanently, perpetually, regularly,
   rigidly, statically, steadfastly, steadily, systematically,
   the world over, unchangingly, universally, unwaveringly,
   without exception