A dependent clause, also known as a subordinate clause, subclause or embedded clause, is a certain type of clause that juxtaposes an independent clause within a complex sentence. For instance, in the sentence "I know Bette is a dolphin", the clause "Bette is a dolphin" occurs as the complement of the verb "know" rather than as a freestanding sentence. Subtypes of dependent clauses include content clauses, relative clauses, adverbial clauses, and clauses that complement an independent clause in the subjunctive mood.

A content clause, also known as a "noun clause", provides content implied or commented upon by its main clause. It can be a subject, predicate nominative, direct object, appositive, indirect object, or object of the preposition. Some of the English words that introduce content clauses are that, who (and formal whom), whoever (and formal whomever), whether, why, what, how, when, and where. Notice that some of these words also introduce relative and adverbial clauses. A clause is a content clause if a pronoun (he, she, it, or they) could be substituted for it.

Examples:

In English, in some instances the subordinator that can be omitted.

Example 1:

Example 2:

In Indo-European languages, a relative clause, also called an adjectival clause or an adjective clause, meets three requirements:

The adjective clause in English will follow one of these patterns: