Existential crisis, or existential despair, was a psychological condition in which an individual questioned the meaning of their life and their existence.
In 3189, upon learning that he had been drinking synthehol from Michael Burnham, Cleveland Booker responded, "Damn. And here I am, trying to get a buzz on and reach a place of existential despair." (DIS: "People of Earth")
At a dinner hosted by Captain Saru, Emperor Philippa Georgiou improvised a haiku after hearing the captain's story of him and his sister drying and gathering their kelp crops on Kaminar. Her haiku: "Kelp dries in the sun / An existential crisis / Is there some dessert?" (DIS: "Forget Me Not")