CLAUSE. In grammatical description, a SENTENCE or sentence-like construction included within another sentence, such as because I wanted to in I did it because I wanted to.

Traditional kinds of clauses

(1) Main clause. A simple sentence consists of one MAIN CLAUSE or principal clause: I knew it. The computer industry is bursting with energy. (2) Coordinate clause. In the following sentence, there are two main clauses, linked through COORDINATION by and. Each is therefore a COORDINATE CLAUSE: They milked the animals and then they made yoghurt, butter, and cheese. (3) Subordinate clause. In the following sentence, there are two clauses, linked through SUBORDINATION by that: Some scientists argue that the earth's climate is changing. In one contemporary analysis, the main clause includes the SUBORDINATE CLAUSE, and is the whole sentence, but in a traditional analysis the main clause is restricted to Some scientists argue. Two subordinate clauses may be coordinated (here with and): We can see that the health of species is interconnected and that the human race is now in danger. One subordinate clause may be subordinated to another, as in I know that everybody believes that it is too late. Both that-clauses are subordinate, but one of them (that everybody believes that it is too late) is superordinate to the that-clause within it (that it is too late). Some grammarians refer to a subordinate sentence or clause as being embedded within its matrix sentence.

Non-finite clauses

In some descriptions, the term clause is restricted to constructions whose verb is finite, as in the examples given so far. Other descriptions extend the term to sentence-like constructions that have a non-finite verb or no verb at all, both of which are PHRASES in traditional grammar. However, they are sentence-like because they can be analysed in terms of such elements as subject and object. In these more recent descriptions, the infinitive clause to value two important pictures in the sentence She was asked to value two important pictures can be analysed as having a verb to value and a direct object two important pictures, corresponding to the analysis of She will value two important pictures. Similarly, the verbless clause obdurate as stone in the sentence Obdurate as stone, the man withstood all pleas can be analysed as consisting of a subject complement, corresponding to the analysis of The man was obdurate as stone. In such a description, sentences are classified by form into three types: finite clauses; nonfinite clauses (infinitive and participle clauses); verbless clauses.

Clauses and functions

The clause can also be classified into three major types: nominal or noun clause, relative or ADJECTIVE CLAUSE, and ADVERBIAL CLAUSE. Nominal clauses have functions similar to those of a noun or pronoun, such as subject or object; for example, the nominal clause that the spacecraft were too big is subject in That the spacecraft were too big was maintained by many critics (compare That view was maintained by many critics) and object in The committee stated that the spacecraft were too big (compare The committee stated that). Relative clauses have a function shared with that of most adjectives, that is, modifying a noun; for example that she was angling for a hereditary peerage modifies rumours in She denied rumours that she was angling for a hereditary peerage (compare malicious rumours). Adverbial clauses have functions shared with those of most adverbs, such as modifying a verb, alone or with some other parts of the sentence, or the sentence as a whole; for example, the clause if the organization is run by an amiable nonentity in the sentence The problems will prove insoluble if the organization is run by an amiable nonentity (compare in the circumstances) and the clause when the museum moves into the new centre in the sentence When the museum moves into the new centre it will organize scholarly exhibitions (compare then). See ABSOLUTE CLAUSE, PARTICIPLE, SUPERORDINATE CLAUSE.