The English language is wonderful, but it can be extremely confusing. There are homonyms, words that sound just alike, yet are spelled differently and have different meanings. Then we have synonyms, words that have the same or nearly the same meaning as another word in the language. As if that isn't enough to confuse people, there are several rules for forming plurals instead of just one. So how do you know which one to use?

There are regular nouns. These are words such as cat, dog, horse, pig, farm, house, etc. To form the plurals of these nouns, it is simple. You just add an s to the end of the word. Then you would have cats, dogs, horses, pigs, farms, houses, etc.

But wait, these aren't the only regular nouns out there. Some regular nouns end in letters like s, x, ch or sh. This would include words such as mess, box, teach, and wish. To form the plural of nouns ending in these letters, you would add “es” to the end. Then you would have messes, boxes, teaches, and wishes.

The rule is different for a regular noun that ends in a consonant + y. This would include words such as baby, destiny, harmony, and tragedy. To form plurals of these words, you would change the “y” to “i” and add “es” to the end of the word. The plurals of these words would then be babies, destinies, harmonies, and tragedies.

Non-count nouns have no plural form because they are already thought to be plural. This would include nouns such as hair, grass, mud, and dress. Example sentences are below.
hair - The plural for countable hair is hairs. One hair, two hairs...But a collection of hair is hair.
Several different styles of hair are worn in this day and age.
grass - If you're speaking of one species of grass the plural would be grass, whereas if you're speaking of multiple species, the plural form would be grasses.
Ten different varieties of grass were displayed during the meeting of farmers.
There is no instance that I know of where 'mud' would have an 's' added to the end in order to make it plural. It is always a non-count noun.
The three kinds of mud each had the same purpose.
dress - Dress is the plural form of dress when referring to a style of dress, not to an article of clothing.
The style of dress was unique to each tribe.

Nouns that end in 'fe' – such as knife and wife- you change the 'f' to 'v' and add 's'. The plurals of these would be knives and wives.

But what if the word just ends in 'f', like the words loaf and half? Well, then you cnange the 'f' to a 'v' and add 'es'. The plurals then would be loaves and halves.

In order to form the plural of words that end in 'us', such as syllabus, you change the 'us' to 'i'. The plural then would be syllabi.

If your word ends in an 'o', such as tomato, you would add 'es' to form the plural. Thus, the plural of tomato would be tomatoes.

In unchanging nouns, the plural form is exactly the same as the singular form. This pertains to quite a few animal nouns. Deer, fish, bison, moose, and elk remain the same whether you are talking about one or more of these animals.

Then there are some plurals that you just need to memorize. Plurals to nouns such as man, woman, person, tooth, and goose are examples of these. The plurals to these words are men, women, people, teeth and geese.

What is the best way to learn all of the correct plural forms of nouns? Read – a lot. Pay attention to the plurals of nouns that you run across in what you read and make it a point to learn them. No matter what nationality you are, no matter what reading or learning problems you have, this is a way to learn them. Even if you happen to be dyslexic (and I am running into more and more people who have this condition), you can still learn the way to properly form the plural of each and every word.