Definition:
An embedded clause (also called a subordinate clause or dependent clause) is a clause that is grammatically nested inside another clause, functioning as a noun phrase (subject or object), an adjective (relative clause), or an adverb (adverbial clause) within the larger sentence structure. Unlike a main clause, an embedded clause cannot stand as an independent sentence: that she arrived is not a complete utterance on its own, but in I know that she arrived, it serves as the object of the verb know. Cross-linguistic variation in how embedded clauses are structured — word order, complementizer placement, verb form, tense agreement — is a major source of difficulty in second language acquisition.
In-Depth Explanation
Embedded clauses fall into several major types based on their grammatical function.
Complement Clauses
Complement clauses serve as the subject or object of a verb or adjective. They are introduced by complementizers (that, whether, if) or are zero-marked:
- She believes that the earth is round.* (object complement)
- That he passed surprised everyone. (subject complement)
- I wonder whether she knows. (indirect question)
Different predicates select different clause types: want selects an infinitival complement (I want to leave), while think selects a finite that-clause (I think that she left). This selectional sensitivity must be learned for each verb.
Relative Clauses
Relative clauses are embedded within a noun phrase, modifying the head noun. English forms them with relative pronouns (who, which, that, whose):
- The book that I borrowed was excellent. (object relative)
- The woman who called is my sister. (subject relative)
Cross-linguistically, Keenan and Comrie’s Noun Phrase Accessibility Hierarchy predicts which positions in a relative clause are most and least accessible for relativization — subject relatives are universally easiest; object-of-preposition relatives are hardest.
Adverbial Clauses
Adverbial clauses modify the main clause, expressing time, cause, condition, concession, etc.:
- I left before she arrived. (temporal)
- Although it rained, we continued. (concessive)
- If you study, you’ll pass. (conditionals)
Japanese Embedded Clauses
Japanese embedded clauses appear before (not after) the head noun, following head-final word order:
- [彼女が買った] 本 (hon) — the book [that she bought] — modifier precedes head
The relative clause 彼女が買った directly precedes 本 (book) without a relative pronoun. This pre-nominal pattern, combined with SOV order, is one of the structurally distinctive features of Japanese syntax that requires explicit attention from English learners.
SLA Relevance
The acquisition of embedded clauses is a reliable developmental marker in L2 syntax. Research shows:
- Finite complement clauses emerge after learners have basic clause structure
- Relative clauses follow the Accessibility Hierarchy in acquisition order
- Cross-linguistic transfer in clause embedding is well-documented
Common Misconceptions
“Embedded clauses are just sentences within sentences.” Not all embedded clauses contain a full finite verb — infinitival complements (I want to leave) and participial clauses (Having finished, she left) are also embedded clauses. The defining feature is grammatical dependence, not surface form.