Crackpot and Pinheaded

Crackpot adjective - Showing or marked by a lack of good sense or judgment.

Pinheaded and crackpot are semantically related. In some cases you can use "Pinheaded" instead an adjective "Crackpot".

Pinheaded adjective - Not having or showing an ability to absorb ideas readily.

Crackpot and pinheaded are semantically related. Sometimes you can use "Crackpot" instead an adjective "Pinheaded".