Plural

In linguistics, noun phrases have grammatical number. Plural is one kind of grammatical number. In English, plural noun phrases are counted as more or less than one (e.g., 32 degrees, no bananas, 0.5 liters, 1.2 grams, two times, three fish, 20 mothers). In contrast, a singular noun phrase usually refers to something that you would count as one only (e.g., one time, a glass, the sun, my mother, Jennifer). Noun phrases that cannot be counted are also singular in English (e.g., water, the meat, some space, etc.).

In many languages, a suffix (word ending) is added to a word to show that the word is plural. In English, the normal plural suffix is -s (e.g., cat is singular, and cats is plural).

 Plurals in English 
There are a number of exceptions:Crystal, David 1995. The Cambridge encyclopedia of the English language. Cambridge University Press, p200/1. Fowler H.W.1965. A dictionary of modern English usage. 2nd ed, revised by Sir Ernest Gowers. Oxford: Clarendon Press, p456.
Singulars ending in s are usually the same in plural: species, mumps, innings and so on. However, proper nouns ending in 's' take add 'es' in plural: Jones becomes the Joneses. 
Compound words add the plural to the noun part: sons-in-law, Lord Mayors, Courts Martial.
Singulars ending in y become ies in the plural if a consonant is before the suffix: day becomes days, but spy becomes spies. Personal names are again exceptions: the plural of Mary is Marys.
Singulars ending in f usually changes to ves: dwarf to dwarves, leaf to leaves, and so on.
Special cases: some plurals just have to be learnt. The plural of person is normally people, but sometimes persons is used.
Invariant nouns: The common names of animals is often used as both singular and plural. One can say "We shot grouse today" correctly no matter what number were killed. With "fish" there is a choice. The traditional English usage is that the word is used for both singular and plural, but American usage seems to prefer fishes as the plural. With groups of animals, one uses the singular, as in a herd of bison or a shoal of herring. However, if the animals are known as individuals then, for example, we feed the ducks, or stroke our cats. There are other cases where there is no plural at all, as with sheep, salmon, deer. Other general words which add no suffix in plural are aircraft and offspring. Some look like singular but are always plural, such as vermin, livestock, cattle, people.

It is fair to say that most native English-speakers make mistakes in this area, which is one of the more troublesome aspects of English.

 Other languages 
All European languages have plural forms. The suffix that is used in each language is different from the one that is applied to English nouns.

In other languages, such as Chinese, Korean and Japanese, there is usually no plural but not for ending.

 References 

Category:Grammar