Countable - non-countable
The difference between count nouns and non-count nouns is important to foreign learners of English. Native speakers are rarely troubled by it.
Logically, it is not hard to distinguish between the two types of noun:
- Count nouns are the names of things which can be counted: such things as 'door' , 'book' and 'ball'.
- Non-count nouns are the names of substances, often liquids, or other things that are not normally counted: 'water' is not an individual thing, and one doesn't easily talk of 'three waters'; 'air' in the sense of atmosphere is indivisible; and the name of the profession 'journalism' is almost always singular.
What is difficult is the various problems of usage. In particular:
- fewer - less
- collective nouns
- words that are non-count in English but count in other languages, such as information
- words whose status is developing or unclear: data, for example.
For a list of examples, see the category of countability examples.
Count nouns are also called countable nouns. Non-count nouns are also called uncountable and mass nouns. Some grammarians use the names countable(s) and uncountable(s). (These are countable nouns, technically speaking.)
Some nouns can be used as either count or non-count: you can have some cake, but also three cakes.