Plurals and Possessives
Many people have trouble keeping straight the rules for spelling plurals and possessives. Like the multiplication tables you learned as a child, the best thing to do is learn these rules by heart. You might still have some trouble remembering them from time to time, but you can correct those issues.
Most nouns have a singular and a plural form. Most commonly, the plural form is created by adding s:
horse — horses
dog — dogs
door — doors
Some nouns that end in f and fe change these letters to v and add es:
thief — thieves
wife — wives
Nouns ending in s, sh, ch, x, and z take on es as a plural ending. For instance:
annex — annexes
witness — witnesses
beach — beaches
Nouns ending in y preceded by a consonant, change y to i and add es; nouns ending in y preceded by a vowel simply gain an s ending:
army — armies
city — cities
key — keys
Rules for nouns ending in o differ. Some form their plural by adding s, while others add es. For instance:
hero — heroes
radio — radios
A few nouns are the same in plural form, such as deer and sheep. Some nouns are always plural, such as acoustics and athletics. Phrases like brother-in-law are made plural by changing the first word: brothers-in-law.
Noun possessives are much easier to figure out. All nouns show possession by either adding 's or s'. If the noun is singular, 's is used; if the noun is plural, use s'. For example:
brother's wife (one brother)
brothers' homes (more than one brother)
Additional confusion arises if the noun in the possessive form ends with s. For example, which is correct?
This depends. Some grammar manuals prefer the former and others the latter. Pick one and stick to it; if you're writing for a specific publisher, you can check with them to see which they prefer.