What is the meaning of Quantifier?

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

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.

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

to quantify

Source: wiktionary.org