WordWeb Online

1. Not responding to treatment
   "a stubborn infection"; "stubborn rust stains";
   - refractory
    
2. Tenaciously unwilling or marked by tenacious unwillingness to yield
   - obstinate, unregenerate

See also: bloody-minded [Brit], bolshie [Brit, informal], bolshy [Brit, informal], bullet-headed, bullheaded, cantankerous, contrarious, cross-grained, determined, disobedient, dogged, dour, down-the-line [informal], hardheaded, inflexible, intractable, mulish, persistent, pertinacious, pigheaded, stiff-necked, strong-minded, strong-willed, stroppy [Brit, informal], sturdy, tenacious, uncompromising, unyielding

Encyclopedia: Stubborn