Formation of plural nouns

An English noun exhibits a two-way distinction of number: a singular form, denoting one of something, and a plural form, denoting two or more. Here are the guidelines for creating plural nouns.

Add -s to form the plural of most nouns.

boy: boys
girl: girls
computer: computers

Add -es if the noun ends in -s, -sh, -ch, or -x.

class: classes
wish: wishes
inch: inches
box: boxes

If a noun ends in consonant + y, change the -y to -i and add -es.

city: cities
lady: ladies

If a noun ends in vowel + y, add -s. Words ending in -quy don't follow this rule (as in soliloquies).

essay: essays
monkey: monkeys

Exception

soliloquy: soliloquies

Add -s to most nouns ending in -f.

Brief: briefs
Chief: chiefs
Proof: proofs

Exceptions: In some cases, change the -f to -v and add -es

Self: selves
Wolf: wolves
Leaf: leaves

In compound words, make the main word plural.

mother-in-law: mothers-in-law
passerby: passersby
sister-in-law: sisters-in-law