adjective

unwilling or unable to change because of tradition or convention.

they are working to change hidebound corporate cultures

conservative,reactionary,conventional,orthodox,fundamentalist,diehard,hard-line,dyed-in-the-wool,ultra-conservative,fixed in one’s views,set in one’s opinions,set in one’s ways,narrow-minded,narrow,petty-minded,small-minded,intolerant,intractable,uncompromising,rigid,prejudiced,bigoted,strait-laced,blimpish