bullheaded (adj.)
- adherent
- adhesive
- balking
- balky
- bigoted
- case-hardened
- closed-minded
- deaf
- dogged
- dogmatic
- fanatic
- gluey
- glutinous
- gummy
- hardheaded
- headstrong
- intolerant
- intractable
- mulish
- obstinate
- opinionated
- overzealous
- persevering
- persistent
- pertinacious
- perverse
- pigheaded
- refractory
- restive
- self-willed
- set
- sticky
- stiff-necked
- strong-willed
- stubborn
- sulky
- sullen
- tacky
- tenacious
- tough
- uncooperative
- unregenerate
- viscid
- willful