WordReference Random House Learner's Dictionary of American English © 2017
ˈmass ˈnoun, n. [countable]a noun that refers to a quantity or mass of things seen as a whole or collection, and therefore not normally having a plural. A mass noun like sugar or sand does not have a plural, unless we refer to a measure or type or kind of such a thing:The noncount meaning of the mass noun sugar appears in "I like sugar.'' The count meaning of the mass noun sugar appears in: "How many sugars (= spoons, packets, or lumps of sugar) do you want in your coffee?''
WordReference Random House Unabridged Dictionary of American English © 2017 mass′ noun′,
Grammara noun, as water, electricity, or happiness, that typically refers to an indefinitely divisible substance or an abstract notion, and that in English cannot be used, in such a sense, with the indefinite article or in the plural.
Collins Concise English Dictionary © HarperCollins Publishers::
mass noun n
- a noun that refers to an extended substance rather than to each of a set of isolable objects, as, for example, water as opposed to lake. In English when used indefinitely they are characteristically preceded by some rather than a or an; they do not have normal plural forms
Compare count noun
'mass noun' also found in these entries: