We found 6 dictionaries that define the word mass nouns:

General (5 matching dictionaries)

1. mass nouns: Merriam-Webster
2. mass nouns: Collins English Dictionary
3. mass nouns: Wiktionary
4. Mass nouns: Wikipedia, the Free Encyclopedia
5. mass nouns: TheFreeDictionary.com

Art (1 matching dictionary)

6. Mass Nouns: Glossary of English Grammar Terms

(Note: See mass_noun as well.)

Definitions from Wiktionary (mass noun) ▸ noun:  A noun that normally cannot be counted. ▸ Also see mass_noun ▸ Words similar to mass nouns ▸ Usage examples for mass nouns ▸ Idioms related to mass nouns ▸ Wikipedia articles (New!) ▸ Words that often appear near mass nouns ▸ Rhymes of mass nouns ▸ Invented words related to mass nouns