Nouns refer to objects and concepts that either can or cannot be counted. Accordingly, only the so-called countable nouns can have a plural form. The plural of countable nouns in English is formed by adding to their singular form the suffix -s or -es, which is pronounced [z] after vowels and voiced consonants (days, dogs), [s] after voiceless consonants (books), and [iz] after -s, -sh, -ch, -x, -z (horses, watches, boxes). The variant -es is used when the singular form of a word ends in -s, -sh, -ch, -x, -z, or -o with a preceding consonant.
table> tables; sea> seas; John> Johns; wish> wishes; potato> potatoes. Also note the spelling changes fe> ve, consonant+y> ie: knife> knives; city> cities.
Plural of the following English nouns is non-standard: man> men; woman> women; foot> feet; tooth> teeth; mouse> mice; child> children; louse> lice; goose> geese; ox> oxen. Some nouns borrowed from Greek and Latin have a special plural form: basis> bases; crisis> crises; phenomenon> phenomena; datum> data; stimulus> stimuli; cactus> cacti. The following nouns have the same form in singular and plural: (this/these) fish, sheep, swine, deer, craft, means, works, headquarters. Manywidely used nouns designating symmetrical objects have only a plural form: trousers, pants, shorts, jeans, trunks, braces, scissors, tongs, scales, glasses, spectacles.
Just like singular nouns, plural nouns also have the possessive case, which is formed by appending an apostrophe to the regular plural suffix -s (pronunciation is not changed) or by using the possessive ending -‘s with non-standard plural forms.
doctors’ offices; knives’ blades; children’s play, these fish’s migration.