stubborn stubborn /ˈstʌbɝn/

adjective

1. () Tenaciously unwilling or marked by tenacious unwillingness to yield  ( obstinate , unregenerate , stubborn )
   tenaciously unwilling or marked by tenacious unwillingness to yield
     The stubborn child refused to eat their vegetables.
   The stubborn child refused to eat their vegetables.
   
2. Not responding to treatment  ( refractory , stubborn )
   not responding to treatment
    A stubborn infection
   a stubborn infection
    A refractory case of acne
   a refractory case of acne
    Stubborn rust stains
   stubborn rust stains