A predicate, or adjective, that expresses the amount of its argument, as in ‘five dollars’ where ‘five’ describes the quantity of dollars. It does not have to be numerical in nature, but can refer to approximate answers to questions such as “How much?” as, as for example, in “A lot of …”. Developmentally, the problem is acquiring the ability to use a quantifier appropriately as in dealing with uncountable nouns (e.g., a little of), countable nouns (e.g., a few of) and applicable to all nouns (e.g., plenty of).
See Arguments (grammar), Linguistics, Predicates (grammar)