Webster's Revised Unabridged Dictionary · 1913

Existential

Existential , adjective

1.
Having existence. [Archaic] — Bp. Barlow
2.
of or pertaining to, or having the character of, existentialism.
3.
(Logic) specifying actual existence, rather than only possibility; as, the existential operator.
Existentially as well as essentially intelligent. — Colerige