flint

Flint is a very hard type of rock. Ever since humans first learned to make tools, back in the Stone Age, they've used flint.

Through history, flint has been used for sharp tools, in walls and buildings, for making sparks to start fires, and in jewelry and pottery. You can also use the word figuratively, to mean a quality of hardness or even cruelty in a someone's personality: "The flint in his nature made him unsympathetic even to the most pitiful crying child."

Primary Meanings of flint

1.
n
a hard kind of stone; a form of silica more opaque than chalcedony
2.
adj
showing unfeeling resistance to tender feelings
Full Definitions of flint
1

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

Types:
gunflint
the piece of flint that provides the igniting spark in a flintlock weapon
firestone
a piece of flint that is struck to light a fire
flintstone
pebbles of flint used in masonry construction
Type of:
silica, silicon dioxide, silicon oxide
a white or colorless vitreous insoluble solid (SiO2); various forms occur widely in the earth's crust as quartz or cristobalite or tridymite or lechatelierite
2

adj showing unfeeling resistance to tender feelings

Synonyms:
flinty, granitic, obdurate, stony
hardhearted, heartless
lacking in feeling or pity or warmth

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