derived from experience or the experience of existence; "the rich experiential content of the teachings of the older philosophers"- Benjamin Farrington; "formal logicians are not concerned with existential matters"- John Dewey
You use existential to describe fear, anxiety, and other feelings that are caused by thinking about human existence and death. `What if there's nothing left at all?' he cries, lost in some intense existential angst. relating to the existence of humans or to existentialism