Parts of speech

Words, or lexemes, are categorised according to the role or function they perform in grammar. These classes are called parts of speech. We can distinguish between open and closed classes of words. The open classes are nouns, verbs, adjectives and adverbs. The closed classes are the determiners, prepositions, subordinators and coordinators. This page provides an overview of these classes and links to more information.


1. Words and lexemes

2. Open classes

3. Closed classes

4. Criteria for class membership

Related pages





Closed classes

Words and lexemes

In linguistics, we make a distinction between words and lexemes. The term 'word' is a non-technical term that we all use every day. For example, all of us will agree on the number of words in the following sentence:

Frida ran ten kilometres yesterday, but she's only running five today. (11 words)

Looking more closely, we can see that ran and running are different forms of the same verb run. The two words involve different inflections of the same lexeme run. The lexeme is the simple form of the word.

We can do more with the words in this sentence – we can assign a category (part of speech) to each according to its grammatical function, for example, Frida, kilometres and she are classified as types of nouns, ten and five are determiners, but is a coordinator and yesterday, only and today are adverbs. The different categories, such as nouns, determiners, coordinators and adverbs, are explained below.

The process of categorising a sentence into parts of speech or assigning functional labels to the constituents is called parsing.

Open classes

Open classes allow new members through borrowing (for example, the noun cafe) and derivation (for example, the adjective bounteous from the noun bounty). Open classes of words include:

Closed classes

Closed classes of words do not allow new members and usually involve grammatical rather than lexical words. Closed classes of words include:

Read more about closed classes...

Criteria for class membership

How are words assigned to different classes?

Parts of speech are often described informally according to the meaning of the words within them. This is not a reliable strategy since 'doing words' for example can be abstract nouns such as activity as well as verbs such as act. Also, one word can be used in different ways in different contexts (consider the word recording which could be a verb or a noun).

A far more reliable way to distinguish among word classes is to compare the way the words are used and the types of endings they can take. As you will see in exploring the pages on specific parts of speech, we can make some general comments about the word endings (morphology) associated with each word class. For example many nouns take the plural suffix -s. For example hand can be the name of the thing on the end of your arm (as in shake hands) and it can also refer to the activity of transferring goods from one person to another (as in hand it over!).

The functions of different word classes also provide us with a consistent way of distinguishing between them. For example both nouns (for example, theatre) and adjectives (for example, comfortable) can act as modifiers in a noun phrase. Compare theatre seats with comfortable seats. Other criteria can then be used to distinguish nouns from adjectives. For example, only theatre can be made plural (theatres) since adjectives do not take number marking.

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