Run-On Sentences: What Are Run-On Sentences? Definition and Examples

If you want to know what run-on sentences are and how to prevent them in your writing, look no further. This article will teach you everything you need to know about what causes them and how to fix them.

In short, a run-on sentence is a sentence that uses incorrect punctuation or conjunctions, making the sentence difficult to read and understand.

This guide is part of our free online Grammar Book.

What Are Run-On Sentences?

Before you can understand a run-on sentence, you need to know what a sentence is and isn't. To be sure, let's have a quick grammar review.

A sentence comprises one or more clauses, each containing a subject and predicate. When you join several clauses together to form a compound, complex, or compound-complex sentence, there are specific rules you need to follow. Sometimes, you end up with run-on sentences if you don't follow those rules.

• So basically, a run-on sentence is a sentence where the clauses aren't connected properly. 

Here are some common ways this happens:

• Comma splice: using commas when it's inappropriate.
• Fused sentence: omitting the punctuation and conjunctions
• Polysyndeton: using too many conjunctions

So let's look at this one by one. One mistake people make is to misuse commas when connecting clauses. That's called a comma splice. It's a common error when connecting two independent clauses together. The proper practice is to join them using either a comma and a coordinating conjunction or a semicolon alone, but people will commonly connect them using just a comma.

Here's an example:

The weather's terrible, we can't go outside. ❌

This often happens when using transitional expressions, like 'therefore' or 'however.'

Case in point:

I'd love to take a nap, however, I have too much to do. ❌

As we saw, another common mistake that creates a run-on sentence is a fused sentence. These happen when there's no punctuation at all and no conjunctions, either.

For instance:

We bought a rubber plant it died we won't be buying any more plants. ❌

And finally, polysyndetons are another type of run-on sentence that use too many conjunctions.

Here's what that looks like:

The dog and the cat and the rabbit all love kale and carrots and peanut butter and they hate apples. ❌

How to Fix Run-On Sentences

Now that we know what run-on sentences are, how can we avoid them in our writing? The first key is to be vigilant. Make sure you check your work and use a grammar checker. When you spot a run-on sentence, you can fix it! How? You're about to find out.

• There are several ways to correct a run-on sentence, depending on the type of error.

Let's look at comma splices first. There are three ways you can fix them:

• replace the comma with a semicolon
• replace the comma with a coordinating conjunction
• switch the sentence up (usually by using a subordinating conjunction)

Let's look at our two comma splice examples from earlier and use all three methods to fix them.

The weather's terrible, we can't go outside. ❌
The weather's terrible; we can't go outside. ✅
The weather's terrible so we can't go outside. ✅
We can't go outside becasuse the weather's terrible. ✅

I'd love to take a nap, however, I have too much to do. ❌
I'd love to take a nap; however, I have too much to do. ✅
I'd love to take a nap but I have too much to do. ✅
I have too much to do, otherwise I definitely would have taken a nap. ✅

When it comes to fused sentences, the problem is slightly different since there are no conjunctions or punctuation at all.

So to fix it, you can:

• add in the appropriate conjunctions and punctuation
• split the sentence into two or three clauses
• switch the sentence up with a subordinating conjunction

We bought a rubber plant it died we won't be buying any more plants. ❌
We bought a rubber plant and it died so we won't be buying any more plants. ✅
We bought a rubber plant and it died. We won't be buying any more plants. ✅
We bought a rubber plant. It died, so we won't be buying any more plants. ✅
We bought a rubber plant. It died. We won't be buying any more plants. ✅
We won't be buying any more plants because we bought a rubber plant and it died. ✅

Finally, with polysyndetons, you can:

• remove some of the conjunctions and use commas instead
• switch some of the conjunctions for more appropriate ones if you see an opportunity to do that
• split the sentence into two or more clauses

The dog and the cat and the rabbit all love kale and carrots and peanut butter and they hate apples. ❌
The dog, the cat and the rabbit all love kale, carrots and peanut butter but they hate apples. ✅
The dog, the cat and the rabbit all love kale, carrots and peanut butter. Thay hate apples, though. ✅

And there you have it! Now you have all the tools you need to go out there and fix any run-on sentence you run into!

Concluding Thoughts

That concludes this article on run-on sentences. I hope you feel a lot more confident that you can avoid them in your writing.

Let's summarize what we've learned:

• A run-on sentence is a sentence where the words and clauses aren't connected properly.
• There are three run-on sentences: comma splices, fused sentences, and polysyndetons.
• You can fix run-on sentences by using one of many techniques, depending on the type of run-on sentence.

If you enjoyed this article, there's more where that came from! Don't forget to check out our Grammar Book; it's a free online database of grammar articles.