What is a Noun?
A noun is a term used by grammarians to designate a certain class of words, or part of speech, in a language. The term noun comes from the Latin nomen, name, the ancient Roman grammatical term, itself a translation from the terminology of the Greek grammarians. The semantic conception of the noun as the name of something has survived in the popular definition: "A noun is the name of a person, place, or thing." Actually, the noun is defined by grammarians by reference to its formal and functional as well as its semantic characteristics.
Formally, the noun may be distinguished from other parts of speech by its inflection, the formal modification of the end of the word: in Latin we recognize, even in advance of learning its meaning, that a word ending in -ibus is a noun. In a language with less inflection the grammarian may rely on another formal differentiator, position in the sentence. In English, where some inflected forms of the noun and verb are identical, the words cook and cooks may be either noun or verb, but in the sentences The cook cooks and The cooks cook relative position indicates which is which. In The cook cooked both position and inflection contribute to the distinction, since the noun cannot have the form cooked.
The semantic attributes of the noun cannot be used in isolation to distinguish it from another part of speech; we may speak of the meaning of the word cook only after we have identified it, through formal means, as noun or verb. At the same time, which of several formally different classes is to be called noun is determined by the semantic and, more important, the functional characteristics of the words in the class.
The semantic range of the noun is typically much wider than that of the verb. Nouns name persons, objects, places, dimensions, ideas, dates, and so forth, and even actions, though these are popularly thought of as being characteristic of verbs. In The factory produced tractors the action is indicated by the verb and the agent by the noun, but in The factory's production of tractors both action and agent are indicated by nouns. Just as the forms of noun and verb may overlap, so also may their semantic ranges.
The crucial differentiator between noun and verb occurs not in the meanings of these words themselves but in the meanings of other elements that typically accompany them and contribute to what grammarians describe as the functioning of the word. A class of words that is accompanied regularly and systematically by indications of time (for example, present, past), aspect (perfective, aorist), or mode (real, unreal) will be labeled verb by the grammarian. A class accompanied by indications of agency, locality, advantage, possession, instrumentality, or any of a host of other meanings (almost anything, indeed, except those associated with the verb) will be labeled noun.
The elements that indicate these accompanying semantic variations may take the form of inflection, position, or auxiliary words. In 'The factory produced tractors' an inflectional device the -ed of produced, informs us that the action took place in past time; relative position in the sentence shows that factory is the performer and tractors the result of the action. But for the noun the most frequent device in English is the auxiliary word, or preposition. The prepositional phrase has two functions in this respect: it helps provide formal identification of the noun, and it gives semantic information that shows the functional relationship of the noun to the rest of the sentence. Words like of, for, to, with, by thus correspond to the case endings of such highly inflected languages as Finnish and Hungarian.
The noun, then, is a class of words that has a very wide semantic range, that is formally differentiated from other classes, and that is regularly accompanied by formal elements providing a type of semantic information different from that which accompanies other classes of words.