Definition of "quantifier"

(grammar) A word, such as all or many, that expresses the quantity of a related noun.  examples

(logic) An operator, such as the universal quantifier (written as ∀) or the existential quantifier (∃), used in predicate calculus to indicate the degree that predicate is true for a specified set.  examples

(computing) A symbol or symbols in a regular expression indicating the number of characters to be matched.  examples