Практическая грамматика

§ 6. The category of number.

English countable nouns have two numbers: the singular and the plural. The main types of the plural forms of English nouns are as follows:

1. The general rule for forming the plural of English nouns is by adding the ending -s (-es) to the singular: flowers, beds, doves, bees, boys etc.

2. If the noun ends in -s, -ss, -x, -sh, -ch, or -tch, the plural is formed by adding -es to the singular:
bus — buses box — boxes bench — benches
glass—glasses brush—brushes match—matches

3. If the noun ends in -y preceded by a consonant, -у is changed into -i before -es.

fly —flies

army — armies
lady — ladies

In proper names, however, adding the ending -s to the singular forms the plural: Mary, Marys.

Note. If the final -y is preceded by a vowel, adding -s to the singular forms the plural.

day — days monkey — monkeys

play—plays toy —toys
key — keys boy — boys

4. If the noun ends in -o preceded by a consonant, the plural is generally formed by adding -es. Only a few nouns ending in -o preceded by a consonant form the plural in -s.

cargo — cargoes hero — heroes
Potato — potatoes echo — echoes
But: piano -—pianos
solo —solos
photo — photos

All nouns ending in -o preceded by a vowel form the plural in -s and not in -es.

cuckoo — cuckoos
portfolio — portfolios

There are a few nouns ending in -o which form the plural both in -s and -es:

mosquito — mosquitos or mosquitoes

5. With certain nouns the final voiceless consonants are changed into the corresponding voiced consonants when the noun takes the plural form.

(a) The following nouns ending in -f (in some cases followed by a mute e) change it into v (both in spelling and pronunciation) in the plural:
wife — wives thief — thieves
knife —knives calf—calves
life —lives half —halves
sheaf — sheaves shelf — shelves
leaf — leaves wolf — wolves
self - selves loaf - loaves

There are some nouns ending in - f which have two forms in the plural:

scarf—scarfs or scarves
wharf — wharfs or wharves
Other nouns ending in -f or -fe add -s in the plural in the ordinary way:
cliff – cliffs
handkerchief - handkerchiefs
II. The plural forms of some nouns are survivals of earlier formations.
1. There are seven nouns, which form the plural by changing the root vowel:
man — men goose — geese
woman — women mouse — mice
foot —feet louse—-lice
tooth — teeth
2. There are two nouns, which form the plural in -en:
ox — oxen
child—children
Note. The noun brother has, beside its usual plural form brothers, another plural form brethren, which is hardly ever used in colloquial language. It belongs to the elevated style and denotes people of the same creed and not relationship.
The noun cow has, beside its usual plural form cows, has the plural kine, which sometimes occurs in poetry.

2. 
   In some nouns the plural form does not differ from the sin­gular: deer, sheep, swine, trout etc.
   

III. Some words borrowed from Latin or Greek keep their Latin or Greek plural forms: e.g. phenomenon - phenomena, datum - data, crisis -crises, stimulus -stimuli, formula - formulae, index - indices etc. Some of these nouns have acquired English plural forms: memorandums, formulas, indexes, terminuses, etc.

The tendency to use the foreign plural is still strong in the technical language of science, but in fiction and colloquial English there is an evident inclination to give to certain words the regular English plural forms in -s. Thus in some cases two plural forms are preserved (formulae, formulas, antennae, antennas).

IV. In compound nouns the plural is formed in different ways.

1. As a rule a compound noun forms the plural by adding -s to the headword:
editor-in-chief — editors-in-chief
brother-in-law — brothers-in-law
looker-on — lookers-on

2. In some compound nouns the final element takes the plural form:

lady-bird — lady-birds

3. If there is no noun-stem in the compound, -s is added to the last element:

forget-me-not —forget-me-nots
merry-go-round—merry-go-rounds

4. When compound nouns are spelled as one word the last element is made plural

bookcase - bookcases
armchair – armchairs

5. If the first words of the compound nouns are nouns man or woman a double plural is used

woman-teacher - women-teachers
man-servant - men-servants

V. Some nouns have only the plural form:

1. The names of things which consist of two similar halves such as scissors, trousers, spectacles, scales, eye-glasses, tongs, breeches, fetters.

2. Nouns, which have collective meaning (concrete or abstract):

1. 
   Concrete: stairs, goods, eaves, slums, outskirts, tropics, memoirs, victuals (провизия), supplies, clothes, sweepings, slops (помои), preserves (консервы), parings (кожура), sweets, belongings.
   

(b) Collective nouns such as cattle, poultry, police etc are always used as plurals (without s-inflexion).

2. 
   Abstract: holidays, tidings, goings-on (поступки), beginnings (also beginning), earnings, wages, contents, proceeds (выручка), riches (богатство) etc.
   

3. In some nouns the final -s loses the meaning of the plural inflexion and the noun is treated as a singular. This is the case with the names of sciences and occupations in -ics:

Mathematics, phonetics, optics, which are usually considered as singular: