Count Nouns vs. Mass Nouns

Mass nouns (also called non-count nouns) have no plural form and can only be counted with the addition of a “measure word.”¹ Mass nouns are often substances or abstract things:

five rices
five grains of rice
five pounds of rice

two waters²
two glasses of water

one sadness, two sadnesses
a lot of sadness at the funeral

Count nouns have a plural form and can be counted without the aid of a “measure word.” Count nouns are often concrete things:

seven books
three children
two grievances

Certain words in English that are used to discuss quantity reflect the distinction between mass and count nouns, but they are often misused. Remember that amount, much, and less should not be used with count nouns; use number, many, and fewer instead:

the amount of books
the number of books

the number of water(s)
the amount of water

much things to see
many things to see

not many homework(s)
not much homework

less children
fewer children

fewer sadness(es)
less sadness

In addition, some mass nouns frequently used in everyday conversation are often mistakenly treated as count nouns, such as homework (see above) and stuff. These mistakes are particularly common among native speakers of Chinese or other East Asian languages who are learning English as a second language.³

three homeworks
three homework assignments

a lot of stuffs
a lot of stuff

¹ In fact, nouns cannot really be so neatly divided into separate categories, since so many of them have multiple meanings and can act as either count nouns or mass nouns depending on context. However, it is vital to understand this fundamental distinction in order to develop a clear and correct sense of English usage.

² In a restaurant, you might ask for “two waters,” but that kind of usage is considered nonstandard.

³ The distinction between mass and count nouns is not a grammatical feature of Chinese, which essentially uses “measure words” (量词) to quantify all nouns.