Most countable nouns have both a singular and a plural form, showing the difference between one and more than one.
The regular way of changing a noun from singular to plural is to add -s at the end.
dog / dogs, chair / chairs, difference / differences
For nouns ending in -y, you drop the -y and add -ies to form the plural.
dictionary / dictionaries, opportunity /opportunities
For nouns ending in –o, you add -es to form the plural.
tomato / tomatoes, potato / potatoes
There are also several irregular ways of forming a plural.
1. With seven nouns you change the vowel. They are:
man / men woman / women
foot /feet goose/ geese mouse/ mice tooth / teeth louse /lice
2. With a few nouns you change the final -f to -ve before adding the -s ending.
knife / knives leaf / leaves wife / wives half / halves
Some nouns in this group have a regular plural as well: scarfs and scarves, hoofs and hooves. Both possibilities are correct.
3. With three nouns you add -en. They are:
ox / oxen, child / children, brother/brethren (only in the religious sense)
4. A few nouns which have been borrowed from foreign languages have an irregular plural. They include:
stimulus / stimuli, crisis / crises, criterion / criteria, phenomenon / phenomena
Often these nouns have two plurals: they have developed a regular plural but have also kept their original irregular one. In these cases, the regular form is more informal and popular; the irregular form tends to be used by specialists.
There are no certain formulas for success. (informal)
We have to learn all the relevant chemical formulae. (specialist)
5. A few nouns have no plural ending, but you can still use them in a singular or plural way: they include the names of some animals (such as sheep, deer, cod), certain nationalities (such as Japanese, Swiss), some nouns expressing quantity (such as ton, p (=”pence)),” and a few others (such as aircraft, crossroads, kennels, offspring).
The sheep was making a noise.The sheep were making a noise.
PLURALS FOR COMPOUND NOUNS
Compound nouns combine two or more words into a single unit. You usually make them plural by adding -s at the end of the word: can-openers, grown-ups. But in a few cases, the first part of the compound takes the -s ending, especially when the compound contains a preposition.
runner-up – runners-up
passer-by – passers-by
man-of-war – men-of-war
Sometimes, a regular plural form has developed, which is slowly replacing the irregular one.
spoonfuls (also spoonsful
mother-in-laws (also mothers-in-law)
NOUNS WHICH ARE ONLY SINGULAR
Several nouns are used only in the singular. There are three main types:
1. Proper names – names of particular people, places, times, occasions, events, and so on.
John, Robinson, Christmas, Tuesday
You can use these in the plural only if you think of them in a countable way. This is especially common with proper nouns expressing time.
On Tuesdays I go swimming.
Are the Robinsons coming to the party?
We stayed with Mary three Christmasses ago
2. Most uncountable nouns, such as music and advice, are only singular.
3. A group of nouns which you use in the singular, even though they end in -s. These include the names of certain subjects, diseases, and games.
physics, linguistics, mumps, measles, billiards
A common mistake is to think of these as plural, and use them with a plural verb or form a singular noun from them.
Linguistics is fascinating. NOT Linguistics are fascinating.
Billiards is a game. NOT Billiards are a game.
Poor Mike’s got measles. NOT Poor Mike’s got a measle.
NOUNS WHICH ARE ONLY PLURAL
Several nouns are used only in the plural. There are three main types:
1. A few nouns are related to things consisting of two joined parts. They include jeans, binoculars, trousers, pliers, scissors. To talk about these in the singular, you use a pair of.
Your jeans are in the wash. NOT Your jeans is in the wash.
I need to buy another pair of jeans. NOT I need to buy another jeans.
NOT I need to buy another jean.
2. A few nouns ending in -s are used only in the plural. They include congratulations, outskirts, remains, stairs, thanks.
The stairs were steep and winding. NOT The stairs was steep and winding
NOT The stair was steep and winding.
These are not uncountable nouns, because they are used with how many, not how much.
How many stairs are there? NOT How much stairs are there?
3. A few nouns express the idea of groups of people or animals. They include people, folk, police, cattle, poultry, livestock.
The police are outside. NOT The police is outside.
NOT The polices are outside.