The standard definition of an adjective
The simplest way to define an adjective is to say that an adjective is a word that describes something, such as the word green in the phrase, “the green grass.” An adjective can give many kinds of information about a noun, such as its color, size, shape, age, and texture, among other things.
Flaws with the standard definition
To think of adjectives simply as descriptive words can sometimes lead one to misidentify an adverb or a determiner as an adjective.
It is important to note that adjectives describe only nouns, and not words from any other word class. For example, the word fast in the phrase “He drives too fast,” is not an adjective. Because it describes the word drive — which is not a noun in this sentence — fast is an adverb in this example. As this example shows, the definition of an adjective as simply “a describing word” is flawed.
The flaw just discussed is relatively easy to spot. Less commonly, determiners may be misidentified as adjectives. For example, the word two in the phrase “two birds” might be thought of as an adjective since it describes something to the reader about the birds. Even though the word two does, in a way, describe a noun in this example, it is still not an adjective. The reasons why are not exactly simple. The following section of this article explains why determiners are not adjectives.
The characteristics of adjectives
The reason why the word two is not an adjective in the phrase “two birds” is because it does not have the characteristics of an adjective, which are as follows:
1) Adjectives have the ability to build off each other indefinitely (in theory) before the noun to which they refer is introduced.
We can have a simple phrase, such as “He drives a small car.”
To this, the adjective new can be inserted, either in front of the word small (“He drives a new, small car,”) or after it (“He drives a small, new car.”)
To this, countless other adjectives can be inserted. For example, the following phrase is perfectly grammatical, though it is awkward (hence, the “in theory” condition): “He drives a small, new, clean, shiny, smooth, comfortable, speedy, cool car.”
Now see what happens when we try to insert the word two: “He drives two small cars,” is an acceptable sentence, but “He drives small, new, clean, two, shiny, smooth, comfortable, speedy, cool cars,” is not. The word two cannot be inserted into a list of adjectives anywhere we want it to. It must be placed before the list.
2) (Most) adjectives can be intensified by words such as really and too.
The word two does not meet this requirement either. We can say, “He drives a really new car,” “. . . a really small car,” “. . . a really clean car,” and so on, but we cannot say, “He drives really two cars.” The word two would come before the intensifier if there are adjectives in the phrase (“He drives two really small, new cars,”) which isolates it from the adjectives.
Note that lacking this characteristic does not mean a word is not an adjective; it only suggests that the word may not be one. Certain adjectives — called absolute adjectives — give a description for something that a thing either is or is not. An example is the adjective stolen — either something is stolen or it isn’t, and one would never remark that something is “very stolen.” Notice how, unlike two, stolen gets placed after the intensifier if it is part of a list of adjectives: “He drives a really small, new, stolen car.”
3) (Most) adjectives can take plain, comparative, and superlative forms.
In other words, adjectives can take the suffixes -er and –est, or they can have the words more and most placed in front of them for comparative purposes. (Absolute adjectives are again excepted.)
One can say, “He drives a newer car than I do,” or “He drives the most comfortable car I’ve ever been in.”
Obviously, the word two does not have this characteristic — nothing can have more “two-ness” than something else. One cannot say, “He drives twoer (or more two) cars than I do.”
4) (Most) Adjectives can take the prefix –un, or they have an opposite term (or both).1
Many adjectives can take the prefix –un to indicate that the noun they refer to is not like the adjective. To describe a car that is nothing like the one in the example with the long string of adjectives above (“. . . a small, new, clean, shiny, smooth, comfortable, speedy, cool car,”) we could use the words unclean, uncomfortable, and uncool. The other adjectives in the phrase cannot have the prefix –un attached to them — unsmall is not a word, for example — but we can still describe that a car is unlike the one in this phrase by using their opposites: big, old, matte, rough, and slow.
Neither of these options is available for the word two. To say that “He drives untwo cars” is not acceptable, and two has no opposite.
Jake Magnum, author of the Magnum Proofreading Blog, is dedicated to helping writers perfect their work. In addition to giving free advice on his blog, Jake helps writers by offering very affordable proofreading services at magnumproofreading.com.
1Some adjectives do not have an opposite or an un- form — red, for example. But such words are still adjectives because they can be slotted into a list of adjectives easily: “He drives a small, new, red, clean, shiny, smooth, comfortable, speedy, cool car.”