In the English language, words are categorised into different classes based on what role they perform in a sentence. Most words belong to several, their function depending on the context they’re used in. Each word class has its own rules for usage, and knowing these allows authors to express themselves accurately and coherently in written communication.

In this article, we’ll look at the main word classes in English and their grammatical functions.

Major word classes

There are 4 major word classes in English, named as such due to the prevalence of their use.

Nouns

Nouns are perhaps the most familiar word class in the English language. They are used to name concrete or abstract things, such as people, places, concepts, actions, and qualities. For example, wheel, New York, democracy, etc. As these examples demonstrate, they cover a wide range of concepts and things.

Nouns can be further broken down into different subcategories.

Common noun: Generic term (uncapitalised) used to refer to common objects, places, things, etc., that have not been individually specified. For example, dog, forest, and house.

Proper noun: Specific term used to identify unique objects, people, places, things, etc., which are always capitalised. For example, India, William Shakespeare, and Google.

Concrete noun: Term denoting an object, place, person, etc., that exists in the physical world. For example, microorganism, Mount Fuji, and rock.

Abstract noun: Word used to describe non-physical things that cannot be perceived or sensed. For example, happiness, monarchy, and luxury.

Countable noun: Nouns that can be quantified and thus can be either singular or plural. For example, village, teeth, and phone.

Uncountable noun: Nouns that operate as one unit and thus cannot be pluralised. For example, aircraft, enthusiasm, and lightning.

Collective noun: Term used to refer to a collection of things, places, or people. For example, team, herd, and cluster. These often form noun phrases, such as cluster of stars.

Gerund: The noun form of verbs, taking the form verb + -ing. For example, swimming, eating, and seeing.

Note also that many words can belong to several of these subclasses.

Adjectives

Adjectives are used to describe the qualities of nouns and noun phrases. They provide a reader with extra information, expanding on the qualities or quantities of the noun. For example, clever, dark, and comfortable. They can be used to describe any aspect of an object, location, or person—from size and shape to personality and emotions.

Adjectives can also be broken down into different subclasses.

Pre-positive adjective: Describing words that appear before the noun they modify. For example, stone wall, tired eyes, and gigantic hill.

Post-positive adjective: Adjectives that follow the noun they modify. For example: The sky was cloudy.

Comparative adjective: Words used to compare the qualities of one thing to another, usually ending in -er. Or, for adjectives that do not have an -er form, more or less can be added in front of it to make a comparison. For example, better, taller, and more expensive.

Superlative adjective: These serve a similar function to comparative adjectives, but describe nouns as being the most or least of something, compared to all other possible examples. For example, best, smallest, and least effective.

Quantitative adjective: Words describing the quantity of a noun or noun phrase. These can be specific or general. For example, several people, numerous revisions, and two hours.

Verbs

Verbs are used to describe actions, states, and occurrences. They are vital for expressing what nouns are doing and tend to link them to the other components in a sentence (usually connecting a subject to an object). Common verbs are be, go, and have.

Verbs can be broken down into several subcategories.

Transitive verbs: Verbs that link a subject to a direct object. For example: She saw the problem.

Intransitive verbs: These are used to describe what the subject is doing, without linking it to an object. For example: The man waited.

Dynamic verbs: Words that describe an action that a subject is performing. For example, run, touch, and increase.

Stative verbs: These are used to describe an ongoing state or condition. For example, be, own, and understand.

Auxiliary verbs: Words that function with a main verb to indicate tense, emphasis, possibility, etc. For example: It might be a good idea. And: It had started by around 2pm.

Adverbs

Adverbs are used to add extra detail to other word types and even full sentences. They are used to answer questions the reader may have—they indicate how something was done, to what degree a characteristic is displayed, the author’s feeling toward the information contained in a sentence, etc.

Misplaced adverbs can drastically change the meaning of a sentence, and thus they should be positioned closely to the words they modify. For example:

I ate the lunch that I bought quickly.

I quickly ate the lunch that I bought. 

Here, the first example suggests that the lunch was bought quickly; the second states that it was eaten quickly. Whilst both can be correct, it’s important that the author makes sure that the adverb clearly modifies the right verb by being positioned close to it.

They should thus be used carefully and read back by the author to ensure that their meaning is accurately understood.

Minor word classes

On top of the 4 major classes, below are 4 minor word classes.

Pronouns

Pronouns are used in place of a noun or noun phrase, referring to either the speaker or the thing being referred to. For example, I, he, she, you, them, it, her, mine, etc. As such, they are dependent on preceding contextual information—the reader or listener needs to know who the pronoun is referring to for it to make sense.

Prepositions

Prepositions are words or phrases that are used to indicate relationships between sentence components. They are used to clarify aspects such as time, location, and direction. For example, of, across, in, out, towards, with, by, etc.

They provide clarity to sentences by illustrating the relationships between words. Incorrect usage, however, can cause significant confusion for the reader and obscure meaning. Read the Author Services Guide To Prepositions here.

Determiners

Determiners are used to introduce a noun, express quantity, and indicate a specific thing, location, or person. They can be broken down into articles (the, a, an), quantifiers (few, several, most), demonstratives (this, these, that), and possessives (your, their, his). They always modify nouns and noun phrases, clarifying what is being referred to.

Conjunctions

Conjunctions are used to link words, phrases, and clauses together, allowing for more complex constructions. For example, and, but, for, yet, so, or, because, etc. They can be coordinating (i.e., used to join two words, clauses, or phrases of equal importance) or subordinating (i.e., used to connect a subordinate clause to a main clause).

Using word classes

Being able to identify word classes and knowing how they function in a sentence will allow you to express your research clearly and improve the quality of your writing. This is fundamentally important in academia, where coherence and expression can potentially alter the impact of your research.

Read our Guide To Prepositions and Guide To British and American English to further improve your written communication skills.

If you want to ensure your thesis or dissertation is free from any grammatical and punctuation errors, MDPI Author Services offers language editing services to students. We provide a comprehensive language edit, correcting grammar, punctuation, and phrasing. Users of our Rapid Service will receive their edit within 1 working day.

Our team of highly skilled English editors have edited over 60,000 papers, with a 97% author satisfaction rate. Our services are available to both MDPI authors and those publishing with other journals. Visit the link above to get a free quote today.