certifiable

That can or must be certified.

Mentally ill to such an extent that involuntary institutionalization is appropriate; crazy.

If any person said to you in 1950 that in seventeen years Miss Stalin would defect to the West, you would rightly have considered that person certifiable. She has now done it, with impressive smoothness and conviction.

A crazy person.

Forget the certifiables who are scrawling Hitler mustaches on pictures of the president.