A subordinate clause, also called a dependent clause, contains a subject and a verb but cannot express a complete thought by itself. It depends on an independent clause and normally begins with a subordinating conjunction, relative word, or noun-clause marker. Subordinate clauses add information about time, cause, condition, description, or an idea.
Key Facts at a Glance
- A subordinate clause contains a subject and a finite verb, but it cannot stand alone as a complete sentence.
- An adverbial clause modifies an action or describes time, cause, contrast, condition, purpose, or manner.
- An adjectival clause, also called a relative clause, modifies a noun or pronoun.
- A noun clause performs a noun function, such as subject, object, complement, or object of a preposition.
- A subordinate clause at the beginning of a sentence normally takes a comma after it.
- A dependent clause becomes a sentence only when an independent clause supplies a complete main thought.
What Is a Subordinate Clause?
A subordinate clause is a grammatical unit with its own subject and verb that depends on another clause for completion. In “because the road flooded,” road is the subject and flooded is the verb, but because signals that the thought is unfinished. The clause becomes complete in “The buses stopped because the road flooded.”
The Purdue Online Writing Lab defines a dependent clause as “a group of words that contains a subject and verb but does not express a complete thought.” That definition captures the two essential tests: internal clause structure and external dependence.
A subordinate clause is not subordinate because it is unimportant. The term describes its grammatical relationship. In “Although the forecast changed, the event continued,” the opening clause supplies a contrast that shapes the meaning of the independent clause.
Clause Anatomy
A clause requires a subject-verb relationship, although the subject may be understood in certain nonfinite constructions. A subordinating element then establishes a relationship between the dependent material and the main clause.
| Sentence segment | Subject | Verb | Status | Function |
|---|---|---|---|---|
| because the road flooded | the road | flooded | Subordinate | Cause |
| The buses stopped | the buses | stopped | Independent | Main action |
| that Mina selected | Mina | selected | Subordinate | Describes book |
| The book was expensive | The book | was | Independent | Main statement |
The word because does not create a clause by itself. It changes the status of the clause that follows it. Remove the connector from “because the road flooded,” and “the road flooded” can stand independently.
How Can You Identify a Subordinate Clause?
Identify a subordinate clause by locating a subject and verb, finding a dependency marker, and testing whether the segment expresses a complete thought alone. The fastest reliable method is to bracket the suspected clause, remove it, and check both its internal structure and its relationship with the remaining sentence.
Use this four-step process:
- Locate every verb. Include auxiliary verbs such as has, will, and could, not only action verbs.
- Match each verb with a subject. In “when the manager arrives,” manager performs arrives.
- Find the connector. Look for words such as although, because, if, when, who, which, or that.
- Apply the independence test. Read the clause alone. If it sounds unfinished, it is dependent.
Consider “We canceled the match because the field was frozen.”
- Independent clause: We canceled the match
- Subordinating conjunction: because
- Subject and verb inside the dependent clause: the field was
- Subordinate clause: because the field was frozen
- Relationship: cause
A useful warning: punctuation cannot identify a subordinate clause by itself. A comma may separate clauses, phrases, or introductory words, so grammar must come before punctuation.
What Are the Three Main Types?
The three main types of subordinate clauses are adverbial, adjectival, and noun clauses. Their names describe the grammatical job each clause performs: an adverbial clause modifies a predicate, an adjectival clause modifies a noun, and a noun clause occupies a noun position.
Adverbial Clauses
An adverbial clause modifies a verb, adjective, adverb, or entire independent clause. It commonly answers when, why, under what condition, despite what, for what purpose, or how.
| Relationship | Common markers | Example | Meaning supplied |
|---|---|---|---|
| Time | when, before, after, while | Call me when the train arrives. | Arrival time |
| Cause | because, since, as | We stayed inside because smoke filled the room. | Reason |
| Condition | if, unless, provided that | If the alarm rings, leave immediately. | Requirement |
| Contrast | although, even though, whereas | Although prices rose, demand remained steady. | Unexpected contrast |
| Purpose | so that, in order that | She whispered so that nobody would hear. | Intended result |
| Manner | as, as if, as though | He spoke as if he knew the answer. | Comparison or manner |
The dependent clause may come first or last. “Because smoke filled the room, we stayed inside” uses a comma after the introductory clause. “We stayed inside because smoke filled the room” usually needs no comma because the cause is closely attached to the action.
Adjectival or Relative Clauses
An adjectival clause modifies a noun or pronoun and usually follows the word it describes. Relative pronouns include who, whom, whose, which, and that; relative adverbs include where, when, and why.
- The engineer who designed the bridge won an award.
- I returned the laptop that you recommended.
- The village where my grandparents lived has expanded.
A relative clause can be restrictive or nonrestrictive. A restrictive clause identifies which person or thing the writer means, so it does not take commas: “The files that contain financial data need encryption.” A nonrestrictive clause adds information about an already identified noun, so it takes commas: “The files, which were encrypted yesterday, are ready.”
Noun Clauses
A noun clause functions as a noun within a larger sentence. It can act as a subject, direct object, subject complement, or object of a preposition.
- What the committee decided surprised everyone.
Subject - The analyst explained why the server failed.
Direct object - The question is whether the contract remains valid.
Subject complement - We disagreed about who should lead the project.
Object of a preposition
Noun clauses often begin with that, what, whether, if, who, how, why, or whatever. The marker that may be omitted when the noun clause is an object: “I believe that the plan will work” and “I believe the plan will work” are both grammatical.
How Do Subordinating Conjunctions Change Meaning?
Subordinating conjunctions change the logical relationship between clauses, so replacing one connector can alter the sentence’s claim. Because gives a reason, although introduces contrast, if states a condition, and unless expresses a negative condition.
Compare these sentences:
- We left because the storm intensified.
The storm is presented as the reason. - We left although the storm intensified.
The departure happened despite the storm. - We left if the storm intensified.
The departure depended on that condition. - We left before the storm intensified.
The departure happened earlier in time.
The conjunction should match the intended relationship, not merely the location of the clause. A common editing error is using since when the reader could interpret it as either time or cause. Replace “Since the system changed, errors increased” with “Because the system changed, errors increased” when causation is intended.
Where Should a Subordinate Clause Go?
A subordinate clause can appear before, after, or inside an independent clause, and placement affects punctuation, emphasis, and processing effort. Introductory clauses often frame the main action, terminal clauses usually create smoother prose, and embedded clauses provide description at the point of reference.
| Placement | Example | Typical punctuation | Primary effect |
|---|---|---|---|
| Introductory | When the bell rang, students left. | Comma after clause | Emphasizes time |
| Terminal | Students left when the bell rang. | Usually no comma | Keeps main action first |
| Embedded restrictive | Students who finished early left. | No surrounding commas | Identifies students |
| Embedded nonrestrictive | Students, who were exhausted, left. | Commas on both sides | Adds extra detail |
Can a Subordinate Clause Begin a Sentence?
A subordinate clause can begin a sentence when an independent clause follows it. Writers commonly place an introductory clause first to establish a condition, setting, reason, or time before presenting the main action.
- If the temperature falls below zero, the pipes may freeze.
- Although the sample was small, the result was consistent.
- After the interview ended, the candidate sent a thank-you note.
The comma marks the boundary between the introductory dependent clause and the main clause. If the opening clause is very short, some styles permit a comma to be omitted, but retaining it improves readability when the boundary could be missed.
When Is an End-Position Comma Optional?
An end-position subordinate clause usually does not take a comma when it supplies essential information about the main action. A comma may be appropriate when the clause is supplementary, strongly parenthetical, or deliberately separated for emphasis.
- The flight was delayed because fog covered the runway.
The reason is closely connected. - The flight was delayed, although passengers had boarded.
The contrast is presented as an afterthought. - When the clause is long or internally complex, a comma may clarify structure, but the writer should first consider rewriting.
Many copyeditors favor no comma before essential adverbial clauses. The exact choice can vary with style guide and meaning, so punctuation should communicate the intended relationship rather than follow a mechanical rule.
How Does a Subordinate Clause Compare With Other Structures?
A subordinate clause differs from a phrase because it contains a subject-verb relationship, and it differs from an independent clause because it cannot stand alone. A compound sentence joins independent clauses, whereas a complex sentence joins at least one independent clause with at least one subordinate clause.
| Structure | Example | Subject and verb? | Complete alone? |
|---|---|---|---|
| Phrase | After the meeting | No finite verb | No |
| Subordinate clause | After the meeting ended | Yes | No |
| Independent clause | The team left | Yes | Yes |
| Compound sentence | The team left, and the office closed | Two clause pairs | Yes |
| Complex sentence | The team left after the meeting ended | Main plus dependent clause | Yes |
A sentence may contain multiple subordinate clauses. “Although the manager agreed that the budget was tight, she approved the purchase because the equipment had failed.” The sentence contains an adverbial clause, a noun clause, and another adverbial clause.
What Is a Reduced Subordinate Clause?
A reduced subordinate clause omits an explicit subject or finite verb when the meaning remains clear. Reduced clauses make prose shorter, but they require the understood subject to match the subject of the main clause.
- Full: After she reviewed the evidence, Priya wrote the report.
- Reduced: After reviewing the evidence, Priya wrote the report.
The understood subject of reviewing is Priya. The following sentence dangles because the grammatical subject does not perform the reduced action: “After reviewing the evidence, the report was submitted.” A report cannot review evidence. Correct it with “After reviewing the evidence, Priya submitted the report.”
When Should Relative Clauses Use Commas?
Use commas around a relative clause when the information is nonrestrictive, and omit commas when the clause identifies the noun. In standard edited American English, that normally introduces restrictive clauses, while which commonly introduces nonrestrictive clauses, although style conventions differ internationally.
- Restrictive: The report that includes raw data is confidential.
- Nonrestrictive: The report, which includes raw data, is confidential.
The first sentence implies that several reports exist and identifies one. The second treats the report as already identified and adds the raw-data detail.
The relative pronoun may be omitted when it functions as the object of the clause:
- The film that we watched won three awards.
- The film we watched won three awards.
It cannot normally be omitted when it functions as the subject:
- Correct: The researcher who discovered the error corrected it.
- Incorrect: The researcher discovered the error corrected it.
The word that also introduces noun clauses, so function matters. In “The claim that the product is safe was disputed,” that the product is safe is a noun clause modifying claim. It is not a relative clause describing a specific product.
Which Mistakes Cause the Most Problems?
The most frequent subordinate-clause errors are sentence fragments, comma splices, faulty attachment, incorrect relative-clause punctuation, and mismatched logical connectors. Each error can be corrected by identifying the clause boundary and then checking the relationship between the dependent and independent clauses.
Fragmented Subordinate Clauses
Incorrect: “The delivery arrived late. Because the address was incomplete.”
The second sentence is a fragment because because the address was incomplete cannot stand independently. Correct versions include:
- The delivery arrived late because the address was incomplete.
- Because the address was incomplete, the delivery arrived late.
A fragment may be intentional in fiction or advertising, but formal academic, technical, and business writing generally requires a complete sentence.
Misplaced or Dangling Modifiers
Incorrect: “We stored the paintings in the gallery that had climate control.”
The clause appears to describe gallery, although the writer may mean that the paintings had climate control. Move the clause beside its intended noun:
- We stored the paintings that required climate control in the gallery.
- We stored the paintings in the climate-controlled gallery.
Faulty Comma Pairing
Incorrect: “The vehicle, that is parked outside, belongs to Lena.”
The clause identifies which vehicle, so commas incorrectly mark essential information. Correct: “The vehicle that is parked outside belongs to Lena.”
If the noun is already specific, a nonrestrictive clause is possible: “Lena’s vehicle, which is parked outside, needs fuel.”
Illogical Connectors
Incorrect: “Although the battery was empty, the phone shut down because it had no charge.”
The sentence is grammatical, but the relationships overlap awkwardly. A clearer version is “Because the battery was empty, the phone shut down.” Choose one connector when one relationship explains the event completely.
How Should Writers Use Them in Different Contexts?
Writers should use short end-position subordinate clauses for clarity, introductory clauses for framing, and embedded relative clauses only when the described noun remains easy to locate. The appropriate choice depends on reader expertise, sentence length, and whether the clause carries essential or supplementary information.
| Context | Recommended pattern | Example length | Main risk |
|---|---|---|---|
| Beginner writing | Main clause + because clause | 8-14 words | Fragment after conjunction |
| Business email | Main clause + condition or reason | 12-22 words | Buried request |
| Academic prose | Main clause with qualified noun clause | 18-30 words | Excessive embedding |
| Fiction | Introductory time or condition clause | 10-25 words | Repetitive rhythm |
| Technical instructions | If clause + imperative | 8-18 words | Ambiguous condition |
For business writing, put the decision or request near the front: “Please restart the service if the warning appears.” The sentence is easier to scan than “If the warning appears after the update has completed and the service has not recovered, please restart it.”
For academic writing, subordinate clauses can express limitation precisely: “Although the trial included 84 participants, its results do not establish long-term safety.” The clause preserves an important qualification without making the claim indefinite.
A practitioner rule of thumb is to limit a sentence to one heavily embedded subordinate clause when readers must act on the information. If a clause contains another clause, consider splitting the sentence.
How Can You Build Better Sentences With Subordinate Clauses?
Build a sentence by writing the independent clause first, selecting the logical relationship, and adding the shortest subordinate clause that supplies the needed information. The best subordinate clause improves precision without hiding the subject, verb, or requested action.
Use this sequence:
- Write the complete main idea: “The team postponed testing.”
- Identify the missing relationship: reason, time, condition, or contrast.
- Add a connector: because, until, if, or although.
- Supply a subject and verb: “because the server overheated.”
- Check punctuation and attachment.
- Remove unnecessary words.
Examples:
- Reason: The team postponed testing because the server overheated.
- Time: The team postponed testing until the server cooled.
- Condition: The team will resume testing if the server stabilizes.
- Contrast: Although the server stabilized, the team postponed testing.
The same independent clause can support different meanings, but the connector controls the reader’s interpretation. That is why replacing although with because is a logic change, not a stylistic edit.
Expert Rules for Clear Subordination
Three editing principles prevent most errors. First, test the clause without its connector, because “the field was frozen” and “because the field was frozen” have different grammatical status. Second, inspect the nearest noun after every relative clause, because readers attach modifiers locally unless syntax strongly prevents it. Third, place the main action early when the sentence gives an instruction, deadline, warning, or decision.
A counterintuitive point concerns introductory clauses. They do not automatically create more formal or sophisticated prose. “When the audit ended, the director resigned” is useful because the timing matters; moving the clause to the end may reduce emphasis without improving clarity.
Another useful distinction concerns while. The conjunction can express time, as in “While the software updated, users waited,” or contrast, as in “While the software is inexpensive, its support is limited.” If the meaning could be read both ways, replace while with during the time that or although.
Subordination is also unsuitable for every sentence. A short independent sentence is often better when the main point must be unmistakable: “The account is locked. Contact support.” Combining those commands into a long conditional sentence can slow response during an incident.
FAQ
Is a subordinate clause the same as a dependent clause?
Yes. Subordinate clause and dependent clause are grammatical synonyms for a clause that contains a subject-verb relationship but cannot stand alone as a complete sentence. Dependent emphasizes its inability to function independently, while subordinate emphasizes its relationship to the main clause.
Can a sentence have two subordinate clauses?
Yes. A sentence can contain several subordinate clauses with different functions. In “When the meeting ended, I explained what the committee had decided because the client had asked,” the opening and final clauses are adverbial, while what the committee had decided is a noun clause.
Does every subordinate clause begin with a conjunction?
No. Many subordinate clauses begin with relative pronouns or relative adverbs, such as who, which, that, where, and when. Some nonfinite subordinate clauses begin with to or an -ing form, as in “To reduce costs, the company changed suppliers” and “After reviewing the file, Ana called.”
Why is “because” sometimes placed at the start?
Because can begin a sentence when its clause is followed by an independent clause: “Because the road flooded, buses stopped running.” Beginning with because emphasizes the reason. The writer must attach the clause to a complete main clause and place a comma after the introductory dependent clause.
Can a subordinate clause contain another subordinate clause?
Yes. Clause embedding is common in formal English. In “I know that the analyst who joined last month found the error,” the noun clause begins with that, and the relative clause who joined last month is embedded inside it to describe analyst.
What is the simplest way to remember the definition?
Remember subject plus verb, but incomplete thought. In “although the shop was open,” shop is the subject and was is the verb, but although makes the thought dependent. Add a main clause, as in “Although the shop was open, nobody entered,” to create a complete sentence.
The Bottom Line
A subordinate clause is a dependent clause with a subject and verb that cannot stand alone. The three main types are adverbial clauses for relationships such as cause or condition, adjectival clauses for noun description, and noun clauses for noun functions. In subordinate clause definition usage and examples, the decisive tests are structure, dependency, function, logical connection, and punctuation. Identify the clause first, then choose its connector and position according to the meaning you want readers to receive.
