Forming Plural Nouns
I. Regular plurals
The regular plural is formed by adding the suffix -s to the singular:
e.g. cat — cats, table — tables.
II. Irregular plurals
1. Nouns in -ss, -sh, -ch, -x
Nouns ending in -ss, -sh, -ch, -x form their plural by adding -es:
e.g. glass — glasses, dish — dishes, peach — peaches, box — boxes.
2. Nouns in -o
Nouns ending in -o form their plural by adding -es if they are used
frequently they have been introduced into English early:
e.g. tomato — tomatoes, hero — heroes
They add -s only if they are of foreign origin or abbreviated words:
e.g. bamboo — bamboos, kilo — kilos.
A number of nouns ending in -o can take both -s and -es:
e.g. tornado — tornados or tornadoes, motto — mottos or mottoes.
3. Nouns in -y
Nouns ending in -y preceded by a consonant form their plural by
changing -y into -i and adding -es:
e.g. fly — flies, country — countries.
Nouns ending in -y preceded by a vowel form their plural by adding -s
only:
e.g. boy — boys, journey —journeys.
4. Nouns in -f or -fe
The following nouns ending in -f or -fe form their plural by changing
the -f into -adding -es:
e.g. calf — calves, wife — wives. These are the following nouns:
calf, life, shelf, half, loaf, thief, knife, self, wife, leaf, sheaf,
wolf
Some nouns ending in -f can either take -s or change the -f into -v-
and add -es
e.g. dwarf— dwarfs or dwarves scarf — scarfs or scarves.
Other nouns ending in -f or -fe form their plural in the regular way:
e.g. handkerchief— handkerchiefs, fife —fifes.
5. Mutation
The following nouns form their plural by a vowel change:
foot — feet, louse — lice, man — men, goose — geese, mouse — mice, woman
— women, tooth — teeth
6. The -en plural
The following nouns form their plural by adding -en to the singular:
brother — brethren (i.e. 'fellow members of a religious society') child
— children ox — oxen.
7. Foreign nouns
Words of foreign origin often form their plural according to the rules
of a specific language:
a) Latin: stimulus — stimuli, larva — larvae, curriculum — curricula,
codex — codices.
b) Greek: basis — bases, criterion — criteria.
c) French: bureau - beueaux
d) Italian: tempo - tempi
However, foreign plurals sometimes occur along with regular plurals:
e.g. index — indices, indexes , antenna — antennae, antennas, which
indicate two different meanings or only the regular plural is used:
e.g. album — albums, metropolis — metropolises.