In the field of linguistics, a sentence is an expression in natural language, and often defined to indicate a grammatical unit consisting of one or more words that generally bear minimal syntactic relation to the words that precede or follow it. A sentence can include words grouped meaningfully to express a statement, question, exclamation, request or command.
As with all language expressions, sentences may contain both function and content words, and contain properties distinct to natural language, such as characteristic intonation and timing patterns.
Sentences are generally characterized in most languages by the presence of a finite verb, e.g. “The quick brown fox jumps over the lazy dog”.
Components of a sentence
A clause consists of a subject and a predicate. The subject is typically a noun phrase, though other kinds of phrases (such as gerund phrases) work as well, and some languages allow subjects to be omitted. The predicate is a finite verb phrase: a finite verb together with zero or more objects, zero or more complements, and zero or more adverbials.
There are two types of clauses: independent and subordinate (dependent). An independent clause demonstrates a complete thought; it is a complete sentence: for example, “I am sad.” A subordinate clause is not a complete sentence: for example, “because I had to move.”
See also copula for the consequences of the verb to be on the theory of sentence structure.
A simple complete sentence consists of a single clause (subject and predicate). Other complete sentences consist of two or more clauses (see below).
One traditional scheme for classifying English sentences is by the number and types of finite clauses:
A simple sentence consists of a single independent clause with no dependent clauses.
A compound sentence consists of multiple independent clauses with no dependent clauses. These clauses are joined together using conjunctions, punctuation, or both.
A complex sentence consists of at least one independent clause and one dependent clause.
A complex-compound sentence (or compound-complex sentence) consists of multiple independent clauses, at least one of which has at least one dependent clause.
Sentences can also be classified based on their purpose:
A declarative sentence or declaration, the most common type, commonly makes a statement: I am going home.
An interrogative sentence or question is commonly used to request information — When are you going to work? — but sometimes not; see rhetorical question.
An exclamative sentence or exclamation is generally a more emphatic form of statement expressing emotion: What a wonderful day this is!
An imperative sentence or command tells someone to do something: “Go to work at 7:30 in the morning”.
Major and minor sentences
A major sentence is a regular sentence; it has a subject and a predicate. For example: I have a ball. In this sentence one can change the persons: We have a ball. However, a minor sentence is an irregular type of sentence. It does not contain a finite verb. For example, “Mary!” “Yes.” “Coffee.” etc. Other examples of minor sentences are headings (e.g. the heading of this entry), stereotyped expressions (Hello!), emotional expressions (Wow!), proverbs, etc. This can also include nominal sentences like The more, the merrier. These do not contain verbs in order to intensify the meaning around the nouns and are normally found in poetry and catchphrases.
Sentences that comprise a single word are called word sentences, and the words themselves sentence words.