Crackpot and Lamebrain

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

Lamebrain and crackpot are semantically related In some cases you can use "Lamebrain" instead the word "Crackpot" as a noun or an adjective.

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

Crackpot and lamebrain are semantically related in mad topic. Sometimes you can use "Crackpot" instead the word "Lamebrain" as a noun or an adjective, if it concerns topics such as eccentric person.