A midlife crisis is a period of doubt and anxiety that some people experience in middle age, when they think about whether their life is the kind of life that they want. I went through my midlife crisis about four or five years ago, when I was forty. A period of psychological doubt and anxiety that some people experience in middle age. mid-life crisis a period of worry and lack of confidence that some people experience when they are about 40 or 50 years old and begin to feel that they are getting old