intractable (adj.)

• adamant
• adamantine
• bullheaded
• contumacious
• defiant
• fractious
• headstrong
• immovable
• immutable
• incorrigible
• indocile
• indomitable
• inelastic
• inextensible
• inflexible
• insubordinate
• intransigent
• irrepressible
• mulish
• obstreperous
• pertinacious
• perverse
• recalcitrant
• refractory
• resistant
• resisting
• restive
• self-willed
• shrewish
• stubborn
• tough
• unalterable
• unbending
• uncontrollable
• uncooperative
• undisciplined
• ungovernable
• unmalleable
• unmanageable
• unruly
• unsubmissive
• unyielding
• wild
• willful