In the singular, they may have the determiner a or an: a sausage; an asterisk.
We ask: How many words/pages/chairs?
We say: A few minutes/friends/chips?
Use these tests for uncountable nouns:
Uncountable (or non-count) nouns cannot be made plural. We cannot say: two funs, three advices or five furnitures.
We never use a or an with them.
We ask: How much money/time/milk? (Not How many?)
We say: A little help/effort. (Not A few.)
Some nouns may be countable or uncountable, depending on how we use them.
We buy a box of chocolates (countable) or a bar of chocolate (uncountable).
We ask: How much time? but How many times? (where times = occasions).
We sit in front of a television (set) to watch television (broadcasting).
Uncountable nouns are often turned into countable nouns by specialists in a particular field.They become part of the jargon of that specialism.
Grass is usually uncountable but botanists and gardeners talk about grasses.
Linguists sometimes talk about Englishes.
Financiers refer to moneys or even monies.
Teas may be used to mean types of tea.
Remember that both countable and uncountable nouns can be divided into concrete and abstract nouns.
The distinction between concrete and abstract nouns is the most important one of all when you are analysing linguistic data. A lot of abstract nouns in a text will have a big impact on its register.
The Plain English Campaign has an excellent website which will tell you more about the stylistic impact of abstract nouns.
Concrete nouns are the words that most people think of as nouns.
They are mostly the names of objects and animals (countable) and substances or materials (uncountable).
Cake, oxygen, iron, boy, dog, pen, glass, pomegranate, earthworm and door are all concrete nouns.
Abstract nouns name ideas, feelings and qualities.
Most, though not all, are uncountable.
Many are derived from adjectives and verbs and have characteristic endings such as –ity, -ness, -ence, and -tion.
They are harder to recognise as nouns than the concrete variety.