1) Plural formation of a few nouns is made by changing the vowel inside.
Man, men; woman, women;
Louse, lice; mouse, mice;
Foot, feet; tooth, teeth.
2) Some nouns do not change, means they have the same singular as
well as plural form.
Sheep, deer (one sheep, four sheep), pair, dozen, hundred, thousand.
I bought three dozen bananas.
3) Some instruments with two parts, some dresses, diseases, games are used as plural; as,
scissors, spectacles, trousers, measles, billiards, assets, news, proceeds.
These are plural in form but the meaning is singular.
4) Sometimes the nouns and names of sciences used as singular; as,
News, Innings, Mathematics, Physics, Politics, Ethics.
5) Some Collective Nouns having singular form are used as plurals; as,
6) Plurals of some Latin or Greek originating nouns follow the rules of Latin or Greek; as, radius, radii; phenomenon, phenomena; axis, axes; basis, bases.
But some of those nouns follow English rules to make plural; as, plural of formula is formulas, but mostly plural of formula is used as formulae.
Some nouns have two different plurals having two different meanings; as
Index, indexes – is used as plural form in books.
Index, indices – is used as plural form in mathematics.
Brother, brothers – is used for sons of the same parent.
Brother, brothers – is used for members of a society or a community.
7) Some compound nouns are connected into their plural forms by making last word plural; as,
travel agent, travel agents; step son, step sons.
Some compound nouns have their plurals by adding s to the main word; as,
But some compound nouns which are used as one word those have plurals by adding s to the singular; as,
8) Some initials also make their plural by adding s; as,
MP, MPs; UFO, UFOs (unidentified flying objects)
9) Uncountable nouns are always in singular form; as,
In singular form some nouns have two meanings but one meaning of plural form; as,
People – nation, men and women.
Peoples – nations.
10) In plural form some nouns have one meaning but two meanings of plural forms; as,
Effect – result.
Effects – results, property
See also-.Plural Formation of Noun, Number.