(flint) noun
1. A dull–colored variety of quartz resembling chalcedony but more opaque; it is very hard, and produces a spark when struck with steel.
2. A piece of such stone, shaped for some purpose, as for striking fire.
3. Anything very hard, obdurate, or cruel.
—v.t. To provide with a flint. [OE]

(flint)
1. A city in central Michigan.
2. A county in NE Wales; 256 square miles; county town, Mold: also Flint′shire (-shir).

(flint), Austin,
1812–86, U.S. physician.
—Austin,
1836–1915, U.S. physiologist and physician; son of the preceding.