Clause (grammar)

A clause is a grammatical unit organized around a predicate and its associated subject, which may be expressed or understood. A written sentence can contain one such unit or combine several. Identifying clauses is a structural analysis rather than a matter of counting punctuation marks.^[ref]

In the original example The bird landed because the wind dropped, the bird and landed form one subject-predicate pairing, while the wind and dropped form another. The latter is introduced as a subordinate clause giving a reason; the first supplies the main assertion. Both occur within a single written sentence.

Separating the units supports explicit accounts of syntax and interpretation. The labels should still follow the language and construction being analyzed: an omitted subject is not automatically evidence that no clause is present. A proposed analysis must state which elements are expressed and which relationships it treats as implicit.

A main clause is a clause that functions as an independent grammatical unit in the construction being analyzed, contrasted with an embedded subordinate clause. It can be accompanied by subordinate material within a larger sentence. Its status concerns the syntax of that construction, not which information seems most surprising.^[ref]

In the original example The pump stopped although the tank was full, the pump stopped supplies the main clause while although the tank was full contributes subordinate material. Moving that material to the beginning gives Although the tank was full, the pump stopped; the main clause is now later in the sentence. Position alone therefore does not identify it.

The example also separates a clause's own subject and predicate from its relationship to surrounding material. Both parts have internal grammatical structure. Annotating those structures and the embedding relation supports reproducible linguistic annotation, while the speaker's beliefs about the two statements remain a separate interpretive question.

A subordinate clause is a clause embedded within a larger grammatical construction, where it supplies part of the structure or interpretation. It contrasts with a main clause in that construction. Subordination describes a relationship among units, rather than merely identifying whichever words occur after a comma.^[ref]

In the original example The sensor stopped because the battery failed, because the battery failed supplies a reason for the main assertion. In I know that the sensor stopped, the embedded material instead supplies what is known. Both contain their own subject-predicate organization, while contributing differently to the larger expression.

A structural analysis can vary the embedded content while preserving its role in the surrounding syntax. Comparing that pattern across examples helps distinguish an embedded grammatical constituent from an unrelated second assertion. The analysis must also keep the grammatical embedding separate from whether the speaker actually believes the embedded content.