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Wiktionary
existential quantifier

n. (context logic English) The operator, represented by the symbol ∃, used in predicate calculus to indicate that a predicate is true for at least one member of a specified set. Verbal equivalents include "there exists" and "there is".

WordNet
existential quantifier

n. a logical quantifier of a proposition that asserts the existence of at least one thing for which the proposition is true [syn: existential operator]