The etymology of the term skinflint is quite literal. It emerged during the 1700s and is derived from the idea of a person so miserly that they would skin a flint to save or gain anything. And since flint is notoriously hard to skin (spoiler alert: it’s impossible), this gives you an idea of the lengths a skinflint would go to save a penny.

"miser, one who makes use of contemptible economy to keep money," c. 1700 ("Dictionary of the Canting Crew"), slang ; literally "kind of person who would skin a flint to save or gain something," from skin (v.) + flint. Flay-flint in same sense is from 1670s.

Etymology [edit] From the phrase skin a flint (“go to extreme lengths for the sake of gain or economy”), from the brittleness and hardness of flint which makes it almost impossible to remove just its skin without shattering it.