Plural Nouns

The usual construction of plural nouns from singular nouns is to add –s or –es to the end of a word.

Singular	Plural
bird	birds
dog	dogs
cat	cats
glass	glasses
house	houses
kindness	kindnesses (add –es to words that end in –s.)

How do you know when to add –s or –es? If a noun ends in any ending but an –s or –ss, add –es to the end of that word to form the plural. Also, If a word ends in ch, sh, x, or z, add –es to the end of the noun:

Singular	Plural
lunch	lunches (add -es)
countess	countesses (add -es)
lens	lenses (add -es)
fish	fishes (add -es)
fox	foxes (add -es)
buzz	buzzes (add -es)

If a word ends in –y, change the y to i and then add –es to create the plural, as shown below.

Singular	Plural
baby	babies
sky	skies
library	libraries

Please note the irregular plural nouns, shown in the following table.

Singular irregular nouns	Plural irregular nouns
child	children
foot	feet
goose	geese
man	men
moose	moose
mouse	mice
ox	oxen
woman	women

Hyphenated nouns are pluralized by adding –s to the noun. In the examples below, law is also a noun. If a word is most likely to be multiplied, it takes the plural; thus, it is not that there is one mother and many laws, but many mothers.

Singular irregular nouns	Plural irregular nouns
mother-in-law	mothers-in-law
father-in-law	fathers-in-law
sister-in-law	sisters-in-law
brother-in-law	brothers-in-law

For words that are derived from foreign languages, watch the singular and plural for proper use. If a Latin word, for instance, ends in –um, it will change to –a; a word ending in –us will change to –i.

Singular Latin word	Plural Latin word
alumna	alumnae (female)
alumnus	alumni (male) (gender neutral, informal: alum)
datum	data
erratum	errata
medium	media
memorandum	memoranda or memorandums
phenomenon	phenomena
stimulus	stimuli

Exceptions exist, of course. Consult a dictionary for the proper use of singular and plural Latin-derived nouns.