Adjectives are a part of speech that may or may not exist in a language, used in some way to alter the meaning of a noun. English uses adjectives extensively to help describe nouns more specifically. Adjectives in English can be organized into a number of discrete groups, and there is a specific sequence these groups follow in sentences, which is known as adjective order.
Adjective order is one of those things in a language that are rarely acknowledged by native speakers, who assimilate the rules subconsciously and ensure their sentences use the correct adjective order without thinking about it at all. In fact, if you were to ask most English speakers what adjective order was, they wouldn’t be able to tell you – but if you were to present them with lists of adjectives and instruct them to order the adjectives in front of a noun, they could do it easily. Adjective order is one of the things that should be taught to non-native speakers of English, to help their English sound natural to the ears of native speakers. Incorrectly ordered adjectives give a sentence a “wrong” feel that native speakers pick up on immediately.
The exact categories that adjectives fall into are not written in stone, and different grammar sources include more or less groups than others. Most have at least six different groups used in adjective order, however, and the sequence tends to be the same.
Directly before the noun come what are sometimes called phrase-making adjectives, or purpose adjectives. These are adjectives which directly describe what the noun is used for, or help to form the complex noun. An example of this might be the racing car, where racing is the purpose adjective.
Before the purpose adjective comes a material description of the noun, if necessary. This adjective tells what the noun is made of, such as the steel racing car. Before the material adjective is the location adjective, telling where the noun comes from, as in the Italian racing car.
Before location comes color, as in the red racing car. Before color is shape, as in the sleek racing car. Before shape comes a description of age, as in the new racing car. Before age is size, as in the small racing car. At the very beginning of the noun phrase come any opinion adjectives, such as beautiful or best, which describe the noun using terms that are subjective.
Most of these adjective groups fit into the adjective order of a noun phrase very specifically, and putting them in the wrong order will make a sentence sound wrong. For example, if we describe our racing car as the beautiful sleek Italian racing car, the adjective order fits the rules discussed above, and everything sounds fine. If, on the other hand, we were to describe it as the Italian sleek racing beautiful car everything is a-jumble, and the sentence fails. On the other hand, some of the groups may occasionally be interchangeable in some circumstances, but this is rare enough that it is not an issue for adjective order – and usually is the result of a specific idiomatic expression.