From Latin 'existere' (to come forth) — 'ex-' + 'sistere' (to stand). Existence as the act of stepping forth into being.
Relating to human existence; in philosophy, concerned with the nature and experience of individual existence and freedom of choice. In common usage, relating to a crisis of meaning or purpose.
From Late Latin 'existentiālis,' from 'existentia' (existence), from Latin 'existere' or 'exsistere,' meaning to come forth, appear, or come into being. The Latin verb combines 'ex-' (out of, from) and 'sistere' (to cause to stand, to place), a causative form of 'stāre' (to stand), from Proto-Indo-European *steh₂- (to stand). The philosophical sense was developed in the nineteenth and twentieth centuries by Kierkegaard, Heidegger, Sartre, and others. Key roots: ex- (Latin: "out of, from"), sistere (Latin: "to cause to stand, set, place"), *steh₂- (Proto-Indo-European: "to stand").
The phrase 'existential crisis' — now used so casually it describes everything from career doubts to choosing a restaurant — originates in Kierkegaard's concept of 'Angst,' the dread that arises from confronting the radical freedom and responsibility of human existence. Kierkegaard would likely be amused that his profoundly unsettling philosophical insight has become a social media caption.