In linguistics, number is a grammatical category that specifies the quantity of a noun or affects the form of a verb or other part of speech depending on the quantity of the noun to which it refers. Grammatical number is distinct from the use of numerals to specify the exact quantify of a noun; number is usually vague. The most common scheme is singular (one thing) contrasted with plural (many things). Other possibilities are dual number, expressing the existence of precisely two instances of the noun, trial number for three of a noun, paucal number for few but not one of a noun, or a collective number that expresses the whole class of the nouns (e.g., mankind).
Languages that distinguish grammatical number commonly do so by inflection. Verbs and other parts of speech may be inflected to agree with the noun. English does this in a limited way: "he sleeps" but "I sleep"; "this chair" but "these chairs". Even in languages such as Mandarin Chinese that do not mark common nouns for grammatical number, pronouns usually have distinct singular and plural forms. Arguably this is not quite the same concept as grammatical number, since we is not the same as multiple instances of I.
Modern English is typical of languages that have singular and plural number. An English plural can correspond to a dual, trial, paucal, or plural in other languages. Here are some examples of irregular singular-plural pairs:
- foot (singular), feet (plural)
- mouse (singular), mice (plural)
- I (singular), we (plural)
And one regular example:
- encyclopedia (singular), encyclopedias (plural)
Non-borrowed English irregular nouns come in several forms:
Some voice a final fricative when in plural:
- knife, knives (/f/ > /v/)
- mouth, mouths (/T/ > /D/)
- house, houses, (unique plural, /s/ > /z/)
These plurals are distinct in pronunciation from the possessive. There is also a trend in some areas to regularize some of these nouns.
Survivors of the Old English weak masculine declination add -en:
- ox, oxen
- auroch, aurochen (archaic)
Other -en adders are irregular for different reasons:
- child, children
- eye, eyen (rare)
- cow, kine (rare)
- brother, brethren (or brothers)
Some nouns have no plural, or are identical when plural and singular:
- fish (or fishes)
Pronouns are irregular precisely because they are so common:
- I, we
- he she it, they
Some nouns are rather transparently irregular because they undergo the process of umlaut:
- man, men
- foot, feet
- mouse, mice
There are several different kinds depending in the starting and ending vowel, but generally, they converge on /i/.
Most of these nouns are also umlauted in the other Germanic languages.
The (regular) English noun plural marker, -s, has three variants:
- -/s/ next to a voiceless consonant other than a fricative
- -/z/ next to a voiced sound other than a fricative, or a vowel
- -/@z/ or -/Iz/ next to /s/, /z/, /S/, /Z/, /tS/ and /dZ/ (the choice of vowel depending on dialect)
Slovene is more complicated:
- babarija (old wives tale) (singular), babariji (two old wives tales) (dual), babarije (three old wives tales)
- hiša (house) (singular), hiši (two houses) (dual), tri hiše (three houses) (plural), šest hiš (six houses) (plural)
- miš (mouse) (singular), miši (two or three mice) (dual := plural)
- jaz (I) (singular), midva/midve (we) (dual + [Masculine/Feminine gender), mi/me (we) (plural [Ma/Fe gender])
- vrata (one door) (singular), dvoje vrat (two doors (dual), tri vrata (three doors (plural), [plural noun with different or same form]
- babine (afterbirth period) (archaic meaning) (singular), babini (two afterbirth periods) (dual), babine (three afterbirth periods), [plural noun with different or same form]
- človeštvo (mankind) (singular), človeštvi (two mankind) (dual), človeštva (three mankind), [collective noun with different form]
- These and similar examples are very often used incorrectly, even in published or electronic dictionaries.
In Hebrew, one can similarly say:
- sefer (book) (singular), sfarim (books) (plural)
- yom (day) (singular), yamim (days) (plural), but yomaim (two days) (dual)
In terms of pronunciation, however, the majority of nouns (and adjectives) in French are not actually declined for number. The -s suffix is not actually pronounced unless the next word starts with a vowel (this is called liaison) and thus does not really show anything; the plural article or other word is the real indicator of plurality. However, plurals still exist in French because irregular nouns, such as those that end in -l such as cheval (horse) form plurals in a different way. Cheval is pronounced [[email protected]], chevaux is pronounced [[email protected]], and this really shows number differences. The same is true for adjectives.
Effect of number on verbs and other parts of speech
Not only nouns can be declined by number. In many languages, adjectives are declined according to the number of the noun they modify. For example, in French, one may say un arbre vert (a green tree), and des arbres verts ([some] green trees). The word vert (green), in the singular, becomes verts for the plural (unlike English green, which remains green).
In many languages, verbs are conjugated by number as well. Using French as an example again, one says je vois (I see), but nous voyons (we see). The verb voir (to see) in the first person changes from vois in singular, to voyons in plural. In English this occurs in the third person (she runs, they run) but not first or second.
Normally verbs agree with their subject noun in number. But in Ancient Greek and Sanskrit neuter plurals took a singular verb. In English, or at least British English, singular nouns collectively referring to people may take plural verbs, as the committee are meeting; use of this varies by dialect and level of formality.
Other qualifiers may also agree in number. The English article the does not, the demonstratives this, that do, becoming these, those, and the article a, an is omitted or changed to some in the plural. In French and German, the definite articles have gender distinctions in the singular but not the plural. In Portuguese, the indefinite article um, uma has plural forms uns, umas.