【Inflexible】 , 【inexorable】 , 【obdurate】 , 【adamant】 , 【adamantine】 mean not to be moved from or changed in a predetermined course or purpose.
All are applicable to persons, decisions, laws, and principles; otherwise, they vary in their applications.
【Inflexible】 usually implies firmly established principles rigidly adhered to; sometimes it connotes resolute steadfastness, sometimes slavish conformity, sometimes mere pigheadedness <society's attitude toward drink and dishonesty was still 【inflexible】 —Wharton > <a morality that is rigid and 【inflexible】 and dead —Ellis > <arbitrary and 【inflexible】 rulings of bureaucracy —Shils >
【Inexorable】 , when applied to persons, stresses deafness to entreaty <more fierce and more 【inexorable】 far than empty tigers or the roaring sea —Shak. > <our guide was 【inexorable】 , saying he never spared the life of a rattlesnake, and killed him —Mark Van Doren > When applied to decisions, rules, laws, and their enforcement, it often connotes relentlessness, ruthlessness, and finality beyond question <nature inexorably ordains that the human race shall perish of famine if it stops working —Shaw > It is also often applied to what exists or happens of necessity or cannot be avoided or evaded < 【inexorable】 limitations of human nature> < 【inexorable】 destiny> <you and I must see the cold 【inexorable】 necessity of saying to these inhuman, unrestrained seekers of world conquest … "You shall go no further" —Roosevelt >
【Obdurate】 is applicable chiefly to persons and almost invariably implies hardness of heart or insensitiveness to such external influences as divine grace or to appeals for mercy, forgiveness, or assistance <if when you make your prayers, God should be so 【obdurate】 as yourselves, how would it fare with your departed souls? —Shak. > <the 【obdurate】 philistine materialism of bourgeois society —Connolly >
【Adamant】 and 【adamantine】 usually imply extraordinary strength of will or impenetrability to temptation or entreaty <Cromwell's 【adamantine】 courage was shown on many a field of battle —Goldwin Smith > <when Eve upon the first of men the apple pressed with specious cant, O, what a thousand pities then that Adam was not Adam-ant —Thomas Moore >
