An adjectival noun is a grammar term that describes when an adjective occupies a noun’s position in a sentence or when a noun occupies the adjective’s spot. In either case, the use of an adjectival noun is designed to make the statement more descriptive, often by adding a light metaphorical context. For instance, calling a person ‘Clumsy’ as though it were his or her name makes the adjective ‘clumsy’ a proper noun and creates a metaphorical description of the named person. These modified words are common in most complex languages, but are particularly common in English, Arabic, Japanese and German.
In order to understand exactly what an adjectival noun is, it is important to know what nouns and adjectives are. In general, a noun is any person, place, thing or idea. This basically means that a noun is anything that is actually ‘something.’ If a person can conceive of a physical or mental existence for the ‘something,’ it is almost certainly a noun. For instance, ‘book’ is a noun because we can all envision a book sitting on a table, but ‘nice’ is not. While a person may be nice or act nice, that is only a description of the person and not the person himself.
An adjective describes a noun to create clarity in its existence. In the above example, a book sitting on a table may be imagined a thousand different ways by a thousand different people. Adjectives allow words to make the noun’s existence clearer, which allows descriptions of it to have more meaning. For example, the book might be a ‘red book’ and the table may be a ‘metal table.’ These two descriptive words have brought the book and its table from a nearly infinite number of variations down to a relatively small number.
When using an adjectival noun, a person uses a word that is usually a noun as an adjective or a word that is often an adjective as a noun. Two common nouns are ‘race’ and ‘horse.’ Both of these words are separate nouns that have their own particular meaning. When used together, one becomes the adjective of the other: ‘race horse’ or ‘horse race.’ Both of those phrases have different meanings because the first word is always seen as the adjective of the second word; either a horse that races or a race featuring horses.
The second use of an adjectival noun, when an adjective is used as a noun, is often part of a partly metaphorical description or overt classification. For instance, ‘French’ is a descriptive word placed on an object: ‘a French person’ or ‘French dressing.’ When used in that way, it is an adjective, but in the phrase ‘the French,’ the word ‘French’ is used as noun to categorize the French people.