An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Of or relating to → existence, especially  human existence.
2) Philo.:  Pertaining to what exists, and is thus known by experience rather  than reason; empirical as opposed to theoretical.
3) Logic: Denoting or relating to a → formula or → proposition asserting the existence of at least one object fulfilling a given condition; containing an → existential quantifier.
4) Of or relating to → existentialism (Dictionary.com).

From L.L. existentialis, → existence, → -al.

Hastiyâl, from hasti, → existence, + -al a suffix of attributes forming adjectives that often become nouns, in this case preferred to -i because hasti ends in -i, → -al.

A symbol of → predicate logic which expresses that the statements within its scope are → true for at least one instance of something. The symbol ∃ is used as the existential quantifier. Existential quantifiers are normally used in logic in → conjunction with → predicate symbols, which say something about a → variable or → constant, in this case the variable being quantified (→ quantify, → quantification).

→ existential; → quantifier.

A philosophical attitude associated especially with Heidegger, Jaspers, Marcel, and  Sartre, and opposed to → rationalism and  → empiricism, that stresses the individual's  unique position as a self-determining agent responsible for the authenticity of his or  her choices (Dictionary.com).

→ existential; → -ism.

An advocate of → existentialism.

→ existential; → -ist.