Definition of "certifiable"

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.

2015, Rosemary Sullivan, Stalin's Daughter, page 311

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

2009 August 22, Bob Herbert, “Voices of Anxiety”, in New York Times‎