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Real Time or Real-Time: When to Use a Hyphen (And When to Skip It)

You’ll find that quite a few things happen in real-time — or is it “real time”? To hyphen or not to hyphen: that is the question. If you find that you’re uncertain, you aren’t alone.

The correct way to spell “real time,” with or without a hyphen, depends on your intended meaning and syntax. If you are using “real time” as a noun or as part of a noun phrase, you likely do not need a hyphen. A hyphen is only necessary (real-time) if you are using the term as a compound adjective and, in that case, the purpose is for added clarity.

It is often confusing, even frustrating, when you find that sometimes a word carries a hyphen, and sometimes it does not. Still, at other times, we simply spell the two words together, such as in “realtime.” While the latter isn’t technically a word (yet), you’ll find it in some instances. 

Continue reading to learn more about the phrase “real-time,” as well as why — and when — to use the hyphen.   

What Do the Phrases Real Time and Real-Time Mean? 

The term “real time,” whether with or without the use of a hyphen, often pertains to the world of technology, and you’ll find that those in the technology or communication industry use it fairly frequently. 

But its standard or simpler definition is that someone communicated or presented something at the same time that the events actually happen (source). 

The term originated back in the early 19th century as a way to reference logic and philosophy. However, it seems to have less of a connection to those particular schools of thought currently.

If you think about it, when you watch the news, and there is an “update” or interruption to regular programming to communicate events that are taking place at that moment — such as a tragic car accident, an important world event, or even a speech by a president or politician — those things are taking place in real time, at that moment.

You’ll note that there is no hyphen in “real time” in the previous sentence, which is intentional. We’ll discuss why that is the case a bit further in the article.

Other times, you may hear the phrase in reference to traffic updates, intelligence that the military depends on to proceed with a mission, and, as we said above, computer or data processing pertaining to technology and communication. 

It’s essentially a “type” of information that describes the way a system both receives and communicates data such that you can use or apply it at that moment. 

More About the Term “Real-Time” as it Relates to Computer Processing

When we think about real-time data in the world of technology or computer processing, it means that someone can receive transmitted data, and it’s available right away — there is no pause or need to wait for something to upload or some algorithm to take effect.

We also frequently refer to this type of computing or computer processing as “reactive computing” because these systems operate based on a real-time constraint, meaning that the program must guarantee that you receive a response within a particular time parameter (source).

Also, when we are talking about real-time data, we’re talking about milliseconds, even microseconds — which is quite literally as fast and as close as you can get to “in the moment.”

These programs are often based on simulations of time, meaning that a software program runs utilizing a time system that mirrors what would happen in real life. Consider video games, for example. They are not reality, of course, but some popular gaming sites and systems operate in simulated real time. 

If you’ve been reading closely, you’re probably wondering why, in some instances, we wrote the words real and time with a hyphen, real-time, and why, in others, we did not.

If you’re scratching your head in confusion, don’t worry — we’ll get into why that is the case next. It all comes down to understanding syntax and the difference between nouns, adjectives, and, more specifically, compound adjectives.  

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Understanding Compound Adjectives

A compound adjective is not very different from a single adjective, a word that describes something and often asks the questions, “what kind?” or “how many?” To put it simply, a compound adjective is when we join two or more adjectives together with a hyphen, and together those two words modify a noun (source).

With that in mind, what about the compound adjective “real-time?” Also, if you spell “real time” without a hyphen, is it still a compound adjective? The simple answer is no. If there is no hyphen, it should not be an adjective in your sentence but, rather, a noun. 

One reason that hyphens, while seemingly insignificant, are essential is that you may find that the meaning of your sentence changes quite a bit without them — if and when they are necessary.

Let’s review a few example sentences using “real time” and “real-time” to understand the difference in meaning better.

Real Time versus Real-Time

“Real time” — without a hyphen — is a noun or, more specifically, an example of two words that function together as a noun phrase. Rather than describing something, “real time” becomes an idea or, in most cases, part of an adverbial phrase — such as with the phrase “in real time.” 

Real Time: A Noun Phrase

Let’s break this down further. Below is an example of “real time” as part of a noun phrase where the word “real” is an adjective, but “time” is a noun. Nonetheless, together, they function as part of a noun phrase.

1.     It had been months since the couple spent real time together.

You’ll note that, in this case, the phrase “real time” is not modifying anything in particular. Here, “real” modifies “time.” It simply defines what the couple did together. 

You’ll often hear people use this phrase to refer to the idea that we often spend time with one another in a distracting setting. In other words, we’re on our phones, watching TV, or otherwise multitasking. In the sentence above, they meant “real time” more as a way to show that the time was intimate, without distraction, and “real.”  

This is slightly different from how you’ll see the term used in an adverbial phrase or adjective, which is much more common. 

In Real Time: An Adverbial Phrase

Here are a few examples showing “real time” as part of an adverbial phrase.

1.     I prefer to get my news in real time versus waiting to learn of it on television.

2.     The weather report showed up on my phone in real time.

In both of the sentences above, the phrase “in real time” functions as an adverbial phrase because it is showing how something occurred — in “real” time, in the moment. Remember that adverbs (and adverbial phrases) are simply words or phrases that show when, where, how, or even why something happened.

Real Time: An Adjective 

Now, let’s take a look at real-time as an adjective. We’ll use the same sentences above, but we’ll change the syntax a bit. Note that syntax simply refers to the placement of words and phrases within a sentence.  

1.     I prefer to get real-time news versus waiting to learn of it on television.

2.     The real-time weather report showed up on my phone. 

You’ll notice that in these sentences, real-time has a hyphen. The reason why is because we are using it as an adjective to describe the news and the weather report, respectively.

So, the simplest way to determine whether or not you need to use a hyphen in the phrase is to ask yourself whether it functions as a noun, as part of an adverbial phrase, or as an adjective. If it is the latter, then use a hyphen. In all other instances, you can leave the hyphen out.

Next, we’ll take a closer look at why this is the case.

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Hyphens: Avoiding Confusion in Your Sentences

Earlier, we stated that the main purpose of the hyphen is to avoid confusion for your readers. This becomes tricky with compound adjectives because if you (or your reader) are not certain what the adjective modifies, your reader may misinterpret your sentence. 

Let’s take a look at an example of how this can occur.  

1.     I saw a child eating monster illustrated on the pages of my book.

2.     I saw a child-eating monster illustrated on the pages of my book.

If you read sentence one closely, you may ask yourself if the child, him or herself, is actually eating “monster,” or if “monster” is the one who feasts on children.

This is where the hyphen becomes critical to understanding since a monster who eats children is quite different from a child who is eating a monster for dinner!

The Importance of Clarification in Real Time

While less likely to cause confusion, the same can happen with the phrase “real time.” Here is an example.

1.     He received the real time data moments after the accident occurred.

In this sentence, your reader may question whether the data itself was “real-time,” or perhaps it was “real” versus “false” or “fake” time data. The only way to avoid that kind of confusion is to make sure you add in a hyphen to create a compound adjective, like this:

1.     He received the real-time data moments after the accident occurred.

Here, “real-time” is a compound adjective where we understand both “real” and “time” to be a singular idea modifying the noun, data. 

Remember, too, that hyphens are not dashes, and they do not function in the same way. To learn more about dashes and how to use hyphens correctly in other phrases, such as “high-quality versus high quality” take a look at the article, “High Quality or High-Quality: Understanding When to Use a Hyphen.”

Simple Ways to Test: When to Use a Hyphen and When to Skip it

Because there are quite a few instances that require you to use a hyphen, and there is not a list of words that you can easily memorize to know for certain, you can perform a simple test to ensure that you use a hyphen when you need to, and skip it when you don’t. 

If you follow a few simple steps, you should be able to figure it out. You’ll first want to find the noun in your sentence since that will be important in helping you answer whether or not you need a hyphen.

Next, locate the adjectives (two or more) that modify your noun. Make sure that they are each describing more about the noun itself. Then, test each adjective alone with the noun in your sentence to see if it alters or changes the meaning — or doesn’t make sense.

Let’s give it a try.

1.     Her <<high-tech OR high tech>> gadget was all the rage among her friends.

The noun in this sentence is “gadget.” The adjectives are “high” and “tech.”  

Now, let’s try each adjective by itself with the noun — you’d have either a “high” gadget or a “tech” gadget. While “tech” could make sense, a “high” gadget doesn’t seem to make sense at all in the context of the sentence. Because of that, you’ll want to make sure that you add the hyphen to ensure clarity of meaning.

Syntax: Another Simple Test to Determine When You Need a Hyphen

One more way to figure out if you need a hyphen is simply to look at where the phrase is in your sentence — or the syntax. 

This isn’t a hard-and-fast rule, but, in general, if the words you are uncertain about come in the middle or beginning of your sentence, they are more likely to be compound adjectives and, therefore, require a hyphen.  

Conversely, if they come at the end of your sentence, they are probably a noun/noun phrase or an adverbial phrase, and you will not need to add a hyphen. This article was written for

Just remember that a compound adjective like “real-time” is going to come before what it modifies. An adverbial phrase like “in real time” is generally going to come after whatever it is modifying.

Final Thoughts

The world of English grammar can sometimes feel like it’s playing tricks on you, especially when it comes to slight differences in meaning and using symbols like hyphens. Don’t feel bad for not understanding all of these grammatical nuances right away —  they’ll come with time, and, in the interim, use the tools and references available to you on this site for help.