In a sentence, an adjective has the role of describing a noun or noun phrase and as such are often referred to for students as “describing words”.
At a low level, students are often introduced to adjectives in both an attributive (“a big dog”) and a predicative (“I’m hungry“) position.
Adjectives can also appear in a postpositive position e.g. heir apparent. Such expressions in English tend to appear from arhaic or literary sources, from loan words or in certain grammatical constructions e.g. those anxious to leave.
Adjectives can be nominalised (i.e. used in the place of nouns) in some cases. For example, “the good, the bad and the ugly” consists of three nominalised adjectives. One way to understand this use is that “the good” stands for “all that is good” or “all who are good”.
Adjectives can be modified by adverbs, for example “he is really cold”.
Adjectives generally follow a particular order when more than one is used. In English, this order is opinion, size, age or shape, colour, origin, material, purpose. However, this order may not always be followed. For example, in the case of the “big bad wolf” which puts size before opinion in order to follow the I-A-O rule instead.
Many adjectives are capable of showing degree through comparative and superlative forms. In English this is usually done by either adding the suffix -er/est or adding more or most before the adjective. Irregular forms also exist. Some adjectives are also said to be “absolute” and as such cannot indicate degree. For example, pregnant or extinct tend not to be used comparatively although it may be possible to say “she looks more pregnant every time I see her” or to determine that of two animals species that are functionally extinct, the one with fewer surviving members is “more extinct” than the other.
Adjectives can also be used restrictively or non-restrictively. When being used restrictively, an adjective is defining its referent noun or noun phrase. For example, “I always take an umbrella on rainy days”. The adjective “rainy” is defining the “days” on which an umbrella is taken. When used non-restrictively, an adjective describes the noun or noun phrase e.g. “It was such a rainy day.” In this use, rainy is describing the day.
In the field of semantics, adjectives can be further described as being intersective, subsective or nonsubsective. When an intersective adjective combines with a referent, both the adjective and referent must be satisfied for it to apply. For example, the phrase “red ball” only applies to an object that is red and is a ball.
With a subsective adjective, the adjective refers to a subset of the referent. For example, “skillful surgeon” refers to the subset of surgeons who are skilled. However, this differs from other intersective adjectives in that the surgeon need not be skillful in general, only in relation to the noun. Similarly, a “proud father” need not be a proud person in general, nor does a “good electrician” need to be a good person in general.
Nonsubsective adjectives can be privative or plain nonsubsective. A privative adjective shows that the object being referred to does not belong to the referent group. For example, a “former president” is in fact not a president, while a “fake banknote” is in fact not a banknote. Plain non-subsective adjectives are used in reference to an object that may or may not belong to the referent group. For example, an “alleged criminal” may or may not actually be a criminal.
