Definition of "Flint" :

noun: a city in southeast central Michigan near Detroit; automobile manufacturing

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

noun: a hard kind of stone; a form of silica more opaque than chalcedony

adjective: showing unfeeling resistance to tender feelings

"His flinty gaze."