Real-time is a common term in engineering texts. It means a system that produces output within a very tight deadline. I am writing a proposal to be read by non-engineers. I just wonder if it is clear to everybody to say: "the algorithm needs to be fast to produce the results in real-time"?

Edit: The problem is that this is a one-page proposal and the guys who are going to read it might be from social or bio sciences. So, I don't have enough space to define everything. I can replace "real-time" by something like "fast". But I just want to keep the things a bit technical but understandable to everybody.

  • 4
    No, it is not clear to everybody (non-engineers). You need to define and explain the term real-time in the proposal ahead of referring to it. "The algorithm needs to be fast to produce the results in real-time" is fine in its own context if you had explained real-time early on.
    – Kris
    Commented Feb 13, 2012 at 6:38
  • @Kris: I just edited the question and added more details. What do you think now?
    – Helium
    Commented Feb 13, 2012 at 7:03
  • You are right, the exact technicalities are not needed in a one page doc. Real-fast might appeal to social/natural sciences audience better than just fast, though. :)
    – Kris
    Commented Feb 13, 2012 at 7:07
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    I think the even majority of people who think they know what real-time means doesn't.
    – Peter G.
    Commented Feb 13, 2012 at 11:54
  • If I watch a live news coverage online, it is real time. When on vacation at a faraway place, if I get to read today's newspaper today, it is real time.
    – Kris
    Commented Feb 13, 2012 at 15:16

5 Answers 5


Maybe I'm a little geeky, but I understand what real time means. It is not a synonym for fast. First let's agree on what it means:
OED noun the actual time during which a process or event occurs
[as modifier] (real-time) Computing relating to a system in which input data is processed within milliseconds so that it is available virtually immediately as feedback to the process from which it is coming.

In your case, you could gloss immediately, at once, right away for the adverbial phrase in real time: the algorithm needs to be fast to produce the results "in real-time" (right away, at once, immediately).

  • real-time does not mean right-away, or immediately. It can mean "at once" assuming the person knows with what it will be happening at once, and that the two phenomena are related. A better definition might be "in concert with", or simultaneous with, or in sequence with. The operative word being "with", which does have a difference connotation than something happening by mere chance at the same time. When something is real-time it means that a result is in sequence with another phenomena by design, as they are somehow intimately connected.
    – davea0511
    Commented Feb 18, 2016 at 21:04
  • There's a very short feedback loop between input and output, basically. I would say that a lot of people wouldn't understand that this is the meaning. Commented May 16, 2016 at 12:44

Even in software engineering it's not widely known, or even uniformaly defined. To embedded systems people it means that the result must be computed in a certain time or it's useless - to other people it simply means that the answer is produced 'live' or essentially immediately rather than offline

  • Thanks mgb. What do you mean by "other people"? Other engineers or generally others? I just edited the question and added more details. What do you think now?
    – Helium
    Commented Feb 13, 2012 at 7:03
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    @Mohsen Note - real time isn't the same as fast. A daily backup that takes 23hr 59min is real time, a video frame display that takes just longer than 1/60s isn't
    – mgb
    Commented Feb 13, 2012 at 7:17
  • Yes, and that's why I am asking the question. I don't want to describe the technical meaning of real-time to the readers and this is not important for me if the readers understand it as I do or not. The only thing I am looking for is that it makes sense to them and they think it is a bit technical, not a casual term.
    – Helium
    Commented Feb 13, 2012 at 8:07
  • I think it's worth noting that checking usage in Google Books for the early 60s, I find the term was usually written real time, but in the most recent decade it's more likely to be real-time, and there's a steadily-increasing number of instances of realtime. Commented Feb 13, 2012 at 15:54

As I understand it, "Real time" means that the system is always guaranteed to produce the results before some arbitrary deadline (see Wikipedia). What that deadline is however, depends on the system. It can be microseconds, and it can be months. So "fast" is not really appropriate here.

I suggest you use "real-time" in your text, but put a short explanation in parentheses right after the first time you use it. Something like:

The analysis package will produce results in real-time (before the enzyme has broken down), so it will be possible to administer the antidote before the patient has died.


As the other answers have shown, this is not commonly agreed upon, even among those who know what it means. Within IT, it means that the data is delivered to the users screen as soon as possible after it has been acquired. Their display should show data as it is now, and is a very challenging requirement, even though the specifics ( exactly HOW real-time they want it ) may end up being discussed at length.

In your case, I would be tempted to say "time-critical" rather than real-time. So "the delivery of the results is time critical, so this algorithm which is part of that is also time-critical" - which is less specific, but indicates that it needs to take place as fast as possible without losing accuracy. It could still be valid, if it were to take 1 hour to run, if that is the fastest is can manage. That is not real-time, but is still time-critical, potentially.


I personally hate the term 'real time' as in English you don't generally define the default position and most people only really understand 'real time'. Similar to the term 'going forward' it's basically nonsense as people don't default to thinking about 'going backward'.

For example, if you Google 'real time all wheel drive' which is a popular product/feature on cars, the first two links are people who are confused as to what it is. What would be the point of having 'all wheel drive' if it wasn't happening in real time? It so happens that it switches between two wheel drive and all wheel drive in 'real time' but putting that in the byline of the car is borderline meaningless to the general public.

For audiences outside your discipline it would be beneficial to explain that these processes generally take longer (or shorter) than the time scale that we think on but this particular system is able to process things in 'real time' or near 'real time' and is therefore beneficial because it gives up to date information, etc. It makes sense within the discipline because everyone has a common frame of reference about how long this process normally takes so if you take a system that used to run at a thousand times slower than real time and get it to near real time that's really impressive but to a lay audience this is meaningless without context.

  • Actually a lot of people by default tend to dwell in the past ... ie. 'going backward'. The confusion about "real time all wheel drive" (a term I've never personally observed) sounds like a marketing gimmick, employed to take advantage of the rapidly increase in popularity of inappropriate use of "real-time". I also find that very off-putting, but it isn't the fault of "real-time" as a phrase but the misuse of it, which really does render the term "real-time" as nonsense. A good synonym for "real-time" is concurrent. You would never say concurrent all wheel drive. Concurrent with what?
    – davea0511
    Commented Feb 18, 2016 at 22:27

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