The Collaborative International Dictionary of English v.0.48:

Stubborn \Stub"born\, a. [OE. stoburn, stiborn; probably fr. AS.
   styb a stub. See Stub.]
   Firm as a stub or stump; stiff; unbending; unyielding;
   persistent; hence, unreasonably obstinate in will or opinion;
   not yielding to reason or persuasion; refractory; harsh; --
   said of persons and things; as, stubborn wills; stubborn ore;
   a stubborn oak; as stubborn as a mule. "Bow, stubborn knees."
   --Shak. "Stubborn attention and more than common
   application." --Locke. "Stubborn Stoics." --Swift.
   [1913 Webster]

         And I was young and full of ragerie [wantonness]
         Stubborn and strong, and jolly as a pie. --Chaucer.
   [1913 Webster]

         These heretics be so stiff and stubborn. --Sir T. More.
   [1913 Webster]

         Your stubborn usage of the pope.         --Shak.
   [1913 Webster]

   Syn: Obstinate; inflexible; obdurate; headstrong; stiff;
        hardy; firm; refractory; intractable; rugged;
        contumacious; heady.

   Usage: Stubborn, Obstinate. Obstinate is used of either
          active or passive persistence in one's views or
          conduct, in spite of the wishes of others. Stubborn
          describes an extreme degree of passive obstinacy. --
          Stub"born*ly, adv. -- Stub"born*ness, n.
          [1913 Webster]

WordNet (r) 3.0 (2006):

stubbornly
    adv 1: in a stubborn unregenerate manner; "she remained
           stubbornly in the same position" [syn: stubbornly,
           pig-headedly, obdurately, mulishly, obstinately,
           cussedly]