A sentence is a sequence of words constructed in accordance with the rules of grammar. Such a group has a sense of completeness and clarity of meaning. It will be constructed around at least one noun phrase acting as the subject of a finite verb, i.e. it will contain at least one main clause The rules of grammar mainly concern the order words must take in a sentence, technically called its syntax and, to a lesser extent, the form words must take, called their morphology.
Sentence 1) below shows standard syntax and morphology (i.e. standard grammar):
Sentence 2) shows non-standard morphology:
Sentence 3) shows non-standard syntax:
A group of words that is a sentence is made obvious to the eye (i.e. in writing) by an opening capital letter and a final full stop, question mark or exclamation mark. It is made obvious to the ear (i.e. in speech) by the use of pauses. It is made obvious to the mind because it makes sense alone.
A sentence may loosely be said to be a coherent group of words that expresses a single complete thought about something (or someone).
A sentence can be one of three main types:
1. A simple sentence is a sentence that contains a single subject and verb, i.e. an independent clause.
2. A compound sentence is a sentence that contains more than one main clause. These clauses must be linked by co-ordinating conjunction or a semicolon.
3. A complex sentence is a sentence that contains a mixture of clause types. A complex sentence must contain (as all sentences) at least one main clause but will also contain a second kind of clause acting as a dependent or subordinate clause. Subordinate clauses often begin with a subordinating conjunction such as however, although, even though, because, etc. There is also a special kind of sentence, often used in speech, called a 'minor sentence'.
A sentence can fulfil one of four functions:
1. It can make a statement. This is called a declarative sentence, e.g. 'I am overweight.' Declaratives usually follow the word order SV (subject first, verb second)
2. It can ask a question. This is called an interrogative sentence, e.g. 'Am I overweight?' and indicated by a question mark. Interrogatives usually follow the word order VS (verb first, subject second)
3. It can demand an action. This is called an imperative sentence, e.g. 'Sit down, please.' indicated by a lack of subject (but 'you' is implied).
4. It can make an exclamation. This is called an exclamatory sentence, e.g. 'What a mess!', indicated by an exclamation mark.
The word 'subject' needs care as it has a particular - and very important - meaning that is quite distinct to grammar and which is different from the meaning you probably usually use. Grammatically speaking, the subject (S) is an element of a clause. It is the word or phrase that the clause tells about - and is usually a noun or noun phrase. In the sentence, 'I gave him a present', 'I' is the grammatical subject and 'gave' is its associated verb in the sentence (in the past tense). In the simple sentence, 'The quick brown fox jumped over the lazy dog', the subject is 'The quick brown fox'. This is a noun phrase that has as its associated finite verb , 'jumped'.
Most English sentences need a subject but sometimes this can be one of the small words (called pronouns) 'it' or 'there'. This type of subject can be tricky to recognise as proper subjects.
Some typical word orders of simple declarative sentences are: SV (subject-verb), SVO (subject-verb-object), SVC (subject-verb-complement) or SVA (subject-verb-adverbial).
Some types of verb transfer their action from their subject onto something else (the thing receiving the action of the verb is called its object). These are called transitive verbs. In the above sentence, the verb 'gave' is transitive as action transfers to the object, the noun 'a present'.
Verbs are called intransitive if they do not transfer action, but, instead, act to tell what their subject is doing, e.g. 'He is working.', 'It died.' Some verbs can be either transitive or intransitive according to their usage in the sentence, e.g. 'He is singing.' (intransitive) and 'He is singing a song.' (transitive).
A few special verbs (stative verbs) have no sense of direct action but, instead, act to make a statement about their subject's state of being. These verbs are called copular or linking verbs, e.g. He seems ill, She is clever, he was a criminal, it appears dark, etc.. The word that follows a stative verb has no action passing on to it so it cannot be called an object; instead, it is termed a complement.
Confusingly, Some verbs can take two objects:
'I gave Sally a present.' (i.e. 'I gave a present to Sally')
In this type of sentence, the object is 'a present' (= the thing given; this is called the DIRECT OBJECT); but there is a second 'object' - the 'receiver' of the direct object. This is termed the INDIRECT OBJECT. Notice that all sentences of this type can be re-written as shown using the word 'to'.
A word that has a closely similar meaning to another word. English has very few true synonyms (e.g. sofa / couch / settee), but many near synonyms, e.g. house - dwelling - home - abode - pad. The existence of synonyms allows variety of word choice according to style and register. A list of synonyms is available in a thesaurus.