Real Dictionary

mass noun
countable noun: A mass noun is a noun such as ' wine' which is usually uncount but is used with 'a' or 'an' or used in the plural when it refers to types of that substance, as in 'a range of Australian wines'.
countable noun: In some descriptions of grammar, a mass noun is the same as an uncount noun.

mass noun in American English
a noun denoting an abstraction or something that is uncountable, and not preceded by a or an: it is typically in a singular construction, but may be singular or plural in form (Ex.: love, girlhood, butter, news)
a 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

mass noun in British English
noun: 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 n