adamant adamantine bullheaded closed to headstrong immovable immutable impersuadable impersuasible impervious inductile inelastic inextensible inextensile inextensional inflexible intractable intractile irresilient mulish nonelastic nonstretchable obstinate perverse pigheaded self-willed stubborn unalterable unamenable unbending unextendible unextensible unflexible ungiving unimpressionable uninfluenceable unlimber unmalleable unmovable unpersuadable unpliant unreceptive unresponsive unsuggestible unsusceptible unswayable untractable unyielding