A noun is a linguistic item which the grammar of a language identifies as one member of a special class or lexical category, distinct from other classes such as verbs and adjectives. Words may be used as nouns if they accept certain semantic and/or grammatical categories such as countability (e.g. count nouns like 'cats' versus mass nouns like 'rice'), case, gender and number. The word noun has been derived from Latin nomen and is cognate with name.
Although the popular understanding of what a noun is assumes that they are simply words that refer to 'things' in the world, linguists argue that nouns can only be defined in relation to other units of language with which they work. A noun, then, might be identified as those units which can serve as the subject or object of a sentence.
Popular usage and traditional grammar books often refer to nouns as a 'part of speech', and define a noun as a 'person, place or thing'. This is an inadequate definition, however, as it leaves vague what a 'thing' might be (e.g. is justice a thing?), and ignores the fact that the identification of a word as a noun typically depends on where in the sentence or clause it occurs, and what with - either more words, or with inflections and affixes that modify words. In English, for instance, it is not obvious whether 'bank' is a noun or a verb until it is used in a larger phrase or sentence.
Nouns can be further divided into various subcategories across the world's languages.
Languages typically further subdivide nouns into noun classes to some degree. This phenomenon is only peripheral in English, seen in the distinction between pronouns in the third person singular: 'he', 'she' and 'it' can express gender, though this is not quite the same as 'grammatical gender' found in languages such as French, where all nouns must be 'masculine' or 'feminine'. As there is nothing obviously female about the French feminine word table ('table'), for instance, we can see that so-called 'genders' are better-labelled 'noun classes'. Other languages have vastly more noun classes, categorising nouns according to physical or abstract properties. For example, the traditional four-class Australian Aboriginal language Dyirbal famously assigns for example 'women', 'fire', 'sun', 'watery objects' and 'dangerous things' to a single noun class named balan, while men as well as for example the moon, rainbows, fishing objects and some animals such as kangaroos and snakes are assigned to a different class named bayi. The third noun class named balam includes all edible fruits and vegetables, while bala includes only trees.
Languages can also recognise proper and common nouns, the former being able to stand alone as the names of specific people, places or things (e.g. 'London'). They usually do not take determiners (e.g 'the') or plurals. Common nouns are further divided into count and non-count (or mass) nouns, and both of these can be either 'abstract' (broadly, non-observable, such as 'justice') and 'concrete' nouns (which can arguably be measured or observed, such as 'table'). These categories are broad generalisations, however, since for example a 'table' could be a real one that the speaker is referring to, or the abstract idea of one.
Just like verbs and adjectives, nouns are content words. This means among others that they belong to an open class to which new words can be added, and have some kind of intrinsic meaning. By contrast, words grouped into functional categories, such as determiners, are a closed class without any real meaning in their own right.
Interaction with other categories
Nouns have a specific distribution, i.e. can only occur with certain other lexical categories, such as prepositions, and a distinct syntactic function (e.g. acting as a subject or direct object in a clause). This interaction between nouns and other word classes results in a larger noun unit, which syntacticians call the noun phrase (NP). This comprises a noun which often serves as the grammatical head and other lexemes such as adjectives which modify it: 'red car', for instance, is an English noun phrase in which 'red' is subordinate to 'car' in the phrase. The NP functions in a sentence in much the same way as a single noun: 'the big book fell off the table' is a sentence in which 'the big book' is an NP acting as the subject, just as 'Fred' does in 'Fred fell off the table'.
In some language families - especially the Indo-European and Semitic languages - common nouns are very often combined with function words known as grammatical articles, such as 'the' and 'a' in English. The articles often mark the grammatical gender as well.
The noun-verb distinction
The distinction between nouns and verbs is generally supposed to be one of the most important language universals. However, some linguists maintain that there are languages which do not distinguish between these two lexical categories.
- Lakoff (1990: 5).
- Daniel Nettle & Suzanne Romaine, Vanishing Voices: The Extinction of the World's Languages, 2000.
- Newer theories of syntax argue that this is a determiner phrase, headed by 'the' in this case and with the NP reduced to 'big book'.
- Likewise, 'Fred' would be analysed in newer syntactic theories as a DP with a 'zero' determiner and incorporating a noun.