The plural form of most nouns is created simply by adding the letter 's' to the end of the word .
- bag - bags
- dog - dogs
- horse - horses
- minute - minutes
But there are some exceptions:-
Nouns that end in -ch, -x, -s, -sh add '-es' to the end of the word.
- box - boxes
- boss - bosses
- bush - bushes
- church - churches
- gas - gases
Most nouns ending in -o preceded by a consonant also form their plurals by adding '-es' .
- potato - potatoes
- tomato - tomatoes
- volcano - volcanoes
However many newly created words and words with a Spanish or Italian origin that end in -o just add an 's'.
- photo - photos | piano - pianos | portico - porticos
Nouns that end in a single 'z', add '-zes' to the end of the word.
- quiz - quizzes
Nouns ending in a consonant + y, drop the y and add '-ies'.
- party - parties | lady - ladies
Most nouns ending in 'is', drop the 'is' and add '-es'.
- crisis - crises | hypothesis - hypotheses | oasis - oases
Most nouns ending in -f or -fe, drop the f and add 'ves'.
- calf - calves | half - halves | wolf - wolves
But this isn't a hard and fast rule:-
- belief - beliefs (believes is a verb form)
- brief - briefs
- chef - chefs
- proof - proofs
- roof - roofs
- cafe - cafes
- safe - safes (saves is a verb form)
There are also a lot of common nouns that have irregular plurals.
Most common nouns connected with human beings seem to be irregular.
- child - children | person - people | man - men | woman - women
Other irregular common nouns are:-
foot - feet | goose - geese | mouse - mice | tooth - teeth
Some nouns have identical plural and singular forms.
- aircraft - aircraft | fish - fish | headquarters - headquarters | sheep - sheep | species - species
In the plural form they still take a plural verb (are / were):-
There is an aircraft in the hangar.
There are some aircraft in the hangar.
There was a fish in the tank.
There were some fish in the tank.
Uncountable nouns on the other hand have no plural form and take a singular verb (is / was ...).
There is a lot of luggage on the plane, but a piece of luggage has gone missing.
Some nouns (especially those associated with two things) exist only in the plural form and take a plural verb (are / were...).
Have you seen my scissors? They were on my desk.
Nouns that stem from older forms of English or are of foreign origin often have odd plurals.
- ox - oxen
- index - indices or indexes
In compound nouns the plural ending is usually added to the main noun.
- son-in-law - sons-in-law
- passer-by - passers-by
Linguists can argue for hours about the plural ending of nouns ending in -us. Many of these words are loanwords from Latin and preserve their Latin plural form, replacing the -us suffix with -i, but of course not all words ending in -us have a Latin origin , and some Latin words ending in -us were not pluralized with -i. hence the argument.
The English plural of virus is viruses, not viri.
Other Latin loanwords that take the regular English plural -es ending include campus - campuses | bonus - bonuses
Latin loanwords that take a -i plural ending include radius - radii | alumnus - alumni
If you want to bait a linguist ask them if the plural of crocus is crocuses or croci, or whether the plural of octopus is octopuses, octopi or octopodes.
Uncountable nouns are always singular.