/ flɪnt; NAmE / noun
1.
[ U , C ] a type of very hard grey stone that can produce a spark when it is hit against steel :
prehistoric flint implements
His eyes were as hard as flint.
2.
[ C ] a piece of flint or hard metal that is used to produce a spark
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WORD ORIGIN
Old English ; related to Middle Dutch vlint and Old High German flins .