bloody-minded
bolshy
bullet-headed
bullheaded
cantankerous
contrarious
crossgrained
determined
dogged
dour
hardheaded
intractable
mulish
persistent
pertinacious
pig-headed
stiff-necked
strong-minded
strong-willed
stroppy
tenacious
unyielding
adamant
adamantine
adherent
adhesive
assiduous
balking
balky
bigoted
bulldogged
bulldoggish
bulldoggy
bulletheaded
cartilaginous
case-hardened
chewy
clingy
cohesive
constant
continuing
contumacious
coriaceous
diligent
dogmatic
durable
enduring
faithful
fanatic
fibrous
firm
fundamentalist
gluey
glutinous
gristly
gummy
hard
hardy
harsh
headstrong
heady
hidebound
aggressive
arrogant
brave
ferocious
fierce
obstinate
rebellious
reckless
stupid
sullen
tough