A group of words cannot be described as a sentence or a clause unless at least one of the words is a verb. In some ways, we can describe it as the most important part of speech because it is the 'action' word that tells the listener or reader what is happening in the sentence. Verbs can be ‘action’ words like run, initiate, judge, throw, but they can also denote less active notions and have more to do with mental processes and perceptions, like see, know, think and so on.
A noun is a word which is used to denote a person (traffic warden, woman, Prime Minister, pianist etc.), a concrete or abstract entity (binoculars, fork, field, truth, incoherence etc.) or a place (office, garden, railway station). These are all common nouns; there are also proper nouns which are the names of a specific person, place, event etc., usually starting with a capital letter, for example, York , John, Christmas, Saturday.
A noun can be extended to a noun phrase. In the example phrases given below, the noun (in the first example) and the noun phrase (in the remaining examples) is in bold. Note how much the noun phrase can be extended by adding extra information each time.
Dogs can be vicious
Some dogs can be vicious
Some of the dogs can be vicious
Some of the bigger dogs can be vicious
Some of the bigger dogs in the dog pound can be vicious
The traditional approach to adverbs has been to assign mainly those words which are made from adjectives by the addition of the ending –ly (quickly, hopelessly), plus certain other words which are difficult to classify, like not, just and soon. Their main function is to qualify the action of the verb in the clause in some way, but they can also be used to add more information to an adjective or other adverb e.g. awfully good, incredibly slowly. The class of adverbs is very wide-ranging in form and is used to add comments to many of the other word classes.
Prepositions allow us to talk about the way in which two parts of a sentence are related to each other. They include words like in, on, under, beside, through, inside, before, opposite. More often than not, these relationships are to do with either time or space, but other types of relationship, such as possession, cause and effect and method can be expressed by using prepositions. The words themselves are generally short and simple but some prepositions are multi-word units; for example, out of, by means of, in spite of, instead of, up to etc. Unless they are part of a verb (get in, pick up, switch off), prepositions are always followed by a phrase containing a noun – at school, in the summer, over the moon and so on.
An adjective gives the reader or speaker extra information about a noun or delimits it in some way. It can occur in two positions in a phrase:
Pronouns are usually treated as a special sub-class of nouns. This is because they stand in for a noun or group of nouns. They are limited in number and belong to what is called a closed set, that is, a group of words to which new members are, for practical purposes, not allowed. Some examples of pronouns are: I, you, he, she, our, its, something, anyone and so on. Thus, instead of saying, Bill’s arrived. Bill’s in the lounge, we prefer Bill’s arrived. He’s in the lounge. Or a person called for you; better would be someone called for you. There are several other words which fall into this class; for example (the) one(s), when used to replace dishes in the example: pass me the dishes - the ones on the top shelf.
It would be very unusual for anyone to either speak or write completely in simple sentences; instead we tend to use a mixture of simple, compound and complex sentences. One way to create longer, more complicated sentences is to use conjunctions. As we have already noted in the section on types of clause, conjunctions serve to connect two or more clauses, phrases or words together to make longer constructions. In the following examples, the conjunction is in bold:
There are two types of conjunction. The first is the coordinating conjunction; examples of this can be seen in sentences a to c above. This type is always used to connect elements that share the same grammatical status, that is, main clause to main clause, verb to verb, noun to noun, adjective to adjective and so on. In sentence a two adjectives, strong and sweet, are conjoined, in b two verbs, go and watch and c two nouns, dog and cats.
The second type is the subordinating conjunction, which most often joins two or more unequal clauses to one another. Typically a main clause will be connected to a subordinate clause as we saw in the section on clause types. So in sentences d to g above, the subordinate clause (which you will remember cannot stand on its own, but needs another more important clause to complete the meaning) begins with a conjunction, here when, because, if and although.
Although the description above may give the impression that any one word within a single meaning belongs exclusively to one word class, you should note that this is not the case. Study the words in bold in the following examples:
This flexibility in word class membership is a peculiar feature of English among the European languages, many of which would require different endings to show the class of the word.