Nouns can typically be divided into two categories: COUNT and MASS nouns. Nouns that are countable (e.g. “one house,” “two houses;” or “one deer,” “two deer” are called “count nouns.” The plural forms of the these nouns are usually made by adding an “s” to the singular forms. For example:
| Singular | Plural |
| horse | horses |
| train | trains |
| boy | boys |
| drink | drinks |
However, some countable nouns have irregular plural forms:
| person | people |
| sheep | sheep |
| man | men |
| fish | fish |
| tooth | teeth |
MASS nouns are things which can’t be counted by themselves because they are always treated as a group, volume, mass or quantity. Some common mass nouns are:
| liquids: | water, oil, gasoline |
| materials: | coal, steel, wood |
| food: | bread, fruit, butter |
| ideas: | love, knowledge, advice |
In order to count mass nouns you must use “amount words” or “quantifiers.” Some examples are:
a pound of butter
three baskets of fruit
four slices of bread
two liters of oil
a glass of water
a grain of sand
two pairs of eyeglasses