Flinty is an adjective that means stern or unyielding.

The word flint, which is derived from Old English, refers to a type of rock known for its hardness and inflexibility. Describing someone as ‘flinty’ means they are inflexible or unwilling to yield to someone else’s way.

Terry isn’t my favorite person to work with. He’s good at his job, but he can be flinty when it comes to doing things his own way.