Where Did the Saying Pigheaded Come from?

While the original meaning of this adjective was, briefly, "having a head resembling a pig's," it's long been used to mean "stupidly stubborn." This figurative meaning comes from the reputation of pigs as being stubbornly willful.

What does it mean to call someone pigheaded?

: refusing to do what other people want or to change your opinion or the way you do something : very stubborn.

Is pigheaded an idiom?

Incredibly stubborn, narrow-minded, and often ignorant or foolish. He's a nice guy most of the time, but he can be really pigheaded when it comes to certain things. My last boss was so pigheaded, so it's nice to work for someone with a bit more common sense and common decency.