Some illustrative examples of English mass nouns:
"There is laundry on my street." ( must be a mass noun ) "There is a laundry on my street." ( must be a count noun )This difference is subtle when phrased in the negative:
"There is no laundry on campus." ( could be either ) "There are no laundries on campus." ( must be a count noun )Another marker of difference between mass and count nouns is "less" and "fewer":
We have less furniture. We have fewer chairs.Many English speakers incorrectly use "less" for both types; in the 1990s several British supermarkets were criticised for their signs above checkouts reading "10 items or less". The correct form is "10 items or fewer": "items" is a count noun, and a mass noun cannot be given a number anyway.
A mass noun can be preceded by a count noun: for example "10 pieces of furniture".
The word "data" is often used as a mass noun, especially by people who work with computers, but this usage is still controversial. In formal writing it retains its original grammatical role as the plural of "datum".