Crackers and Empty-headed

Crackers adjective - Having or showing a very abnormal or sick state of mind.

Empty-headed and crackers are semantically related. In some cases you can use "Empty-headed" instead an adjective "Crackers".

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

Crackers and empty-headed are semantically related. Sometimes you can use "Crackers" instead an adjective phrase "Empty-headed".