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Language Arts


A sentence is one of the foundational elements of writing, but the definition of a sentence as “a complete thought” is not always helpful. This article explores ways of understanding what a sentence is, including a definition and examples.

Defining a Sentence

Here are some sentence definitions rephrased a bit from actual definitions that I found:

  • “A group of words expressing one or more than one complete thoughts.”
  • “A group of words with a subject and verb, beginning with a capital and ending with some kind of end punctuation.”
  • "A group of words with a subject and predicate and able to stand on its own.”

Let’s examine these definitions in helping us to discover what a sentence is. We can do this by taking some examples and seeing if they meet the definition:

1. Yummy!

2. Ralph standing in the woods.

3. “The world is very different now.” (from John F. Kennedy’s Inaugural Address)

Each of these examples meets the criteria of one of the definition. Example 1. expresses a complete thought, meeting the first definition. Apparently someone has tasted something and found it scrumptious. There is nothing more to say. But this sentence doesn’t meet the criteria for the second definition, not having either a subject or a verb (though the implied subject is This (thing that I am eating) and the implied verb is tastes. We should note, though, that in accord with definition three, though it doesn’t have a subject or a verb, it can stand on its own.

The second example has a subject and a verb and meets the capitalization and end punctuation criteria of the second definition. It is not, however, a complete thought, and it does not have a predicate, which requires a different verb form.

The third example meets the criteria of the second and third definitions. It is properly punctuated, has a subject (The world) and a verb imbedded in a predicate (is very different now), but it is not a complete thought. If it were complete, President Kennedy would not have had to go on, as he in fact did, to explain what he meant by “very different.” If the sentence were a complete thought, it would need no amplification.

These three types of definitions are typical and responsible for a lot of confusion about sentences. Let’s go back to the drawing board.

The Sentence in Context

First, let’s consider that perhaps different elements may stand for a sentence in different situations. Even in the most formal meeting of the board of a major corporation, there are times when “Aye!” or “Nay!” would be taken as a complete thought. So might a phrase like “To business.” which is clearly interpretable as “Let us now turn our attention to business,” or something of the sort. Certainly in informal settings, various types of interjections are acceptable as sentences (for more information, see the article “Interjections.”)

It is in the context of formal school papers or essays or other formal writing when the question comes up of whether what one is writing what will be construed as acceptable sentences.

Checking for Complete Sentences

I advise using grammatical criteria instead of trying to figure out how to apply the rule about “complete thoughts.” In other words, in this context, unless you are quoting what someone else said or wrote, in which case you must use the exact words they did or clarify how you are altering it, it is best to create sentences that have a subject and a predicate. 

If you check for both a subject and a predicate, then you will avoid the problem of sentence fragments - sentences that, like example 2 - are judged to be incomplete because they are lacking a necessary part. But there is a second important thing to do if you have more than one independent clause (a subject and predicate that could function as a sentence): check to be sure that they are joined properly. This step will help you avoid run-on sentences, another problem that can occur.

Avoiding Run-On Sentences

There are several acceptable ways to treat consecutive independent clauses:

  • Make them into separate sentences.
  • Join them using a comma and a conjunction, such as and, but, or or.
  • Join them using a semicolon or a colon.

Here’s an example:

I’m going to buy raisins you should buy lemons.

This is a run-on sentence: two independent clauses that have neither been properly divided nor properly joined. Here are three different fixes following the suggestions above:

I’m going to buy raisins. You should buy lemons.

I’m going to buy raisins, and you should buy lemons.

I’m going to buy raisins; you should buy lemons.

The differences are small, but they can make a large difference in how your writing is perceived.

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