Mass noun

A mass noun is a noun which refers to something without clear boundaries or individual members, like milk and gold. The opposite of a mass noun is called a count noun.

Comments
In English, mass nouns cannot be pluralized (cf. *milks) and cannot be used with the indefinite article (cf. *a milk) or with numerals (cf. *one milk).

Mass nouns like cattle and furniture are sometimes called collective nouns because they refer to a collection of individuals, but not to any one individual.

Synonym
mass term

Link
Utrecht Lexicon of Linguistics

Other languages
German Massennomen