An Introduction to WORD CLASSES

An Introduction to  Word Classes

You may find that other grammars recognise different word classes from the ones listed here. They may also define the boundaries between the classes in different ways. In some grammars, for instance, pronouns are treated as a separate word class, whereas we treat them as a subclass of nouns. A difference like this should not cause confusion. Instead, it highlights an important principle in grammar, known as GRADIENCE. This refers to the fact that the boundaries between the word classes are not absolutely fixed. Many word classes share characteristics with others, and there is considerable overlap between some of the classes. In other words, the boundaries are "fuzzy", so different grammars draw them in different places. 

We will discuss each of the major word classes in turn. Then we will look briefly at some MINOR word classes. But first, let us consider how we distinguish between word classes in general.  
  
  

Criteria for Word Classes

We began by grouping words more or less on the basis of our instincts about English. We somehow "feel" that brother and car belong to the same class, and that brother and drives belong to different classes. However, in order to conduct an informed study of grammar, we need a much more reliable and more systematic method than this for distinguishing between word classes. 

We use a combination of three criteria for determining the word class of a word:  
 

1. The meaning of the word 
2. The form or `shape' of the word 
3. The position or `environment' of the word in a sentence

1. Meaning

Using this criterion, we generalize about the kind of meanings that words convey. For example, we could group together the words brother and car, as well as David, house, and London, on the basis that they all refer to people, places, or things. In fact, this has traditionally been a popular approach to determining members of the class of nouns. It has also been applied to verbs, by saying that they denote some kind of "action", like cook, drive, eat, run, shout, walk. 

This approach has certain merits, since it allows us to determine word classes by replacing words in a sentence with words of "similar" meaning. For instance, in the sentence My son cooks dinner every Sunday, we can replace the verb cooks with other "action" words: 
 

My son cooks dinner every Sunday 
My son prepares dinner every Sunday 
My son eats dinner every Sunday 
My son misses dinner every Sunday

On the basis of this replacement test, we can conclude that all of these words belong to the same class, that of "action" words, or verbs. 

However, this approach also has some serious limitations. The definition of a noun as a word denoting a person, place, or thing, is wholly inadequate, since it excludes abstract nouns such as time, imagination, repetition, wisdom, and chance. Similarly, to say that verbs are "action" words excludes a verb like be, as in I want to be happy. What "action" does be refer to here? So although this criterion has a certain validity when applied to some words, we need other, more stringent criteria as well. 

2. The form or `shape' of a word

Some words can be assigned to a word class on the basis of their form or `shape'. For example, many nouns have a characteristic -tion ending: 
 

action, condition, contemplation, demonstration, organization, repetition

Similarly, many adjectives end in -able or -ible: 
 

 acceptable, credible, miserable, responsible, suitable, terrible

Many words also take what are called INFLECTIONS, that is, regular changes in their form under certain conditions. For example, nouns can take a plural inflection, usually by adding an -s at the end: 
 

car -- cars 
dinner -- dinners 
book -- books

Verbs also take inflections (additional parts to the infinitive form of the verb to change their tenses): 
 

walk -- walks -- walked -- walking

3. The position or `environment' of a word in a sentence

This criterion refers to where words typically occur in a sentence, and the kinds of words which typically occur near to them. We can illustrate the use of this criterion using a simple example. Compare the following: 
 

[1] I cook dinner every Sunday 
[2] The cook is on holiday

In [1], cook is a verb, but in [2], it is a noun. We can see that it is a verb in [1] because it takes the inflections which are typical of verbs:  
 

I cook dinner every Sunday 
I cooked dinner last Sunday 
I am cooking dinner today 
My son cooks dinner every Sunday

And we can see that cook is a noun in [2] because it takes the plural -s inflection 
 

The cooks are on holiday

If we really need to, we can also apply a replacement test, based on our first criterion, replacing cook in each sentence with "similar" words: