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.
Origin of mass noun
First recorded in 1930–35
Also called noncount noun, uncountable noun, uncount noun.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for mass 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 normal plural formsCompare count noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012