flint
noun.
a hard kind of stone; a form of silica more opaque than chalcedony
noun.
a river in western Georgia that flows generally south to join the Chattahoochee River at the Florida border where they form the Apalachicola River
Synonym: flint river
noun.
a city in southeast central Michigan near Detroit; automobile manufacturing
adj.
showing unfeeling resistance to tender feelings
his flinty gaze|the child's misery would move even the most obdurate heart