Grammatical number

Grammatical number is a linguistic feature used to express quantity. It allows speakers to distinguish between one, two, three, or more items. This distinction is applied to nouns, pronouns, adjectives, and through verb agreement. In many languages, number is a morphological category. This means the form of a word changes through inflection to show quantity. For example, in English, the noun "apple" is singular, while "apples" is plural. This number information can also appear on demonstratives like "that" or "those." It can even affect the verb, such as using "is" for one item and "are" for many.

To function as a grammatical category, a language must follow specific rules. Every noun form must belong to a specific number class. These classes are disjoint, meaning a word cannot belong to two at once. Furthermore, modifiers like adjectives or verbs may use different forms to agree with the noun. This process is known as agreement. In English, nouns and pronouns are mostly singular or plural. However, some words like "fish" or "cannon" can be either depending on the context. English adjectives do not change for number, and many verb forms remain the same for both singular and plural.

Languages also distinguish between count nouns and mass nouns. Count nouns are items that can be freely used in singular and plural forms. Mass nouns, such as "milk," "gold," or "furniture," are normally invariant. They do not change their form to show quantity. However, a speaker might occasionally use a mass noun as a count noun. A cheesemaker might refer to different types of milk as "milks" to group them. This allows for the enumeration of different kinds of a substance.

There are several distinct types of number systems used globally. The most common is the singular and plural distinction. Singular denotes exactly one referent, while plural denotes more than one. Some languages, like Latin, change nouns, verbs, and adjectives to show number. Others, like Wambaya, mark number on nouns but not on verbs. More complex systems include the dual, trial, and paucal numbers. The dual number refers to exactly two items. In languages with an obligatory dual, the plural term is reserved for three or more items.

The trial number is a rarer category that denotes exactly three items. It is most frequently found in the Austronesian language family. Some languages, such as Awa or Arabana, use trial numbers for nouns. However, it is much more common to find trial numbers used in pronouns. For example, the language Nukna has a single trial pronoun. The paucal number represents a small, inexact group, meaning "a few." The range of a paucal varies significantly. In Warndarrang, it might only go up to five. In Manam, it can be used for groups of more than 20.

History shows that these systems are constantly shifting. The dual number was present in Proto-Indo-European around 4000 BCE. Many of its descendants have since lost this specific category. It survived in Proto-Germanic and was inherited by Old English. While most modern Indo-European languages have lost the formal dual, traces remain. English still uses words like "both," "either," and "neither" to hint at this old distinction. Some languages, like Slovene, have managed to keep the dual in their modern forms.

The distribution of grammatical number is not uniform across the world. Many languages in western and northern Eurasia require plural marking for all nouns. In contrast, languages in Southeast Asia and Australia often use optional plural marking. Some languages in New Guinea lack plural marking entirely. There is also a correlation with morphological typology. Isolating languages, such as those in West Africa, tend to favor no or non-obligatory plural marking. This demonstrates how different linguistic structures organize the concept of quantity.