Complex Sentences: What Is a Complex Sentence?

Complex sentences in English grammar are not referred to as such because they contain complex thoughts or ideas. Rather, “complex” in grammar terms concerns a sentence’s structure.

The Definition of a Complex Sentence

A complex sentence in English grammar is one that has one independent clause and at least one dependent clause.

An independent clause is one that contains a subject and a verb and that can stand alone as a sentence. Conversely, a dependent clause includes a subject and a verb but cannot stand alone as a sentence. It is made dependent by a subordinating word, and it needs to be accompanied by an independent clause to form a clear, complete expression.

Example

While I was talking to my sister, the cat ran into the front yard.

This is a complex sentence. It has an independent clause, the cat ran into the front yard, that could work as its own sentence. It also includes a dependent clause, while I was talking to my sister, that would be a fragment if left on its own. To illustrate this point, let’s separate them:

The cat ran into the front yard. (This sentence is clear and complete.)

While I was talking to my sister. (This is a sentence fragment because it represents an incomplete thought. We are left wondering what happened while you were speaking with your sister.)

Let’s look at another example:

Because I was late for work, I decided to call a taxi instead of wait for the bus.

This is a complex sentence as well. The independent clause is I decided to call a taxi instead of wait for the bus. The dependent clause is Because I was late for work.

We can inspect this sentence the same way we did the first.

I decided to call a taxi instead of wait for the bus. (This sentence can stand alone as clear and complete.) 

Because I was late for work. (This is a sentence fragment with an incomplete thought.)

The Value of Knowing Complex Sentence Structures

Understanding complex sentences is good for a couple of reasons. The first is to simply have a better understanding how English is organized for precise and eloquent writing. The more you know about English grammar, the better writer and communicator you can become.

The second reason is to ensure that you are forming complex sentences where they are useful or needed and avoiding sentence fragments. Leaving dependent clauses on their own leads to choppy, unfinished prose that distracts from the points you wish to make.

Visit Soon for Even More Grammar Tips

Some sentences might be complex, but grammar doesn’t have to be. If you want to enhance your performance at school or work or simply polish your daily communication with anyone, our website offers a wealth of tips and advice you can apply. Come back often to continue learning. You can also ask a question about this post in the comments below!

If the article or the existing discussions do not address a thought or question you have on the subject, please use the "Comment" box at the bottom of this page.

2 responses to “Complex Sentences: What Is a Complex Sentence?”

1. Bobking says:

   November 5, 2021, at 4:33 pm

   Thank you so much. I hope that you’ll share more lessons, because I want to improve my English grammar.

2. Magdalena Algarin says:

   October 4, 2023, at 8:32 am

   This is excellent! Cleft sentences can be confusing but you did a great job of explaining, as many sites do not.