WordWeb Online

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

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

Antonym: docile

Encyclopedia: Stubborn