Are there two widely accepted meanings for digital?

  • Countable number of states (modes) such as on/off etc.

    • Suitable for "things which aren't defined as signals"
  • Discrete in both time and in value

    • Suitable for "things which are defined as signals"


This question shouldn't be marked as a duplicate of this question because the other question is not about if there are two extremely common (macro and micro) definitions for digital, or not.

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    $\begingroup$ @DanBoschen I see. To be more precise, I am referring to the definition of "digitalness" in the context of information processing: whether we can represent a data set by a finite number of states. $\endgroup$
    – AlexTP
    Mar 19, 2022 at 13:30
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    $\begingroup$ @MarcusMüller With all respect to O&H (and you!) I would argue (and did in the linked post) that a definition that excluded discrete in time would be a valid description of something that is still digital. My thoughts are influenced by continuous time S/H circuits, whose value we could represent with digital values if we quantized magnitude only. Would/could such a continuous time output still be considered digital as long as we (only) quantized the magnitude? $\endgroup$ Mar 19, 2022 at 14:21
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    $\begingroup$ digits in some number system. Without the discreteness in time, I don't see how we can describe things in a number of samples! (but now, the thing with AlexTP's stronger requirement for the amplitudes not only being countably many, but even finite, is, that it is sufficient for finite-digit representation of every single sample. It's not necessary – there's infinite discrete distributions with finite entropy!) $\endgroup$ Mar 19, 2022 at 14:31
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    $\begingroup$ @MarcusMüller I may have to modify / change my other answer-- in thinking it through this is exactly how I would distinguish the sides of an A/D and D/A converter, consistent with our buddies and authoritarians O&H $\endgroup$ Mar 19, 2022 at 14:34
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    $\begingroup$ So, here I'm stuck between Authority (with a capital "A") saying something that I myself find insufficient (because discrete amplitude also allows for infinite discrete distributions where each sample might need infinite digits for representation) and @AlexTP's definition that I find overly restrictive (because many distributions, and in fact, those that we'll find useful, I guess, can be discrete-infinite support, finite entropy), but kind of — practical, I guess? I can look at a system and say "oh, it outputs this set of values at this set of times, that's digital", I can't see the P(X). $\endgroup$ Mar 19, 2022 at 14:34

2 Answers 2


Digital Waveform: Discrete in time (or other dependent variable such as Frequency) and discrete in magnitude.

Digital Data: Information represented by discrete symbols selected from a finite alphabet (such as digits).

Other digital "items" with regards to electronics and signal processing are items that consist of or have to do with digital waveforms or more generally digital data.


Would it be correct to say that there are two common, distinct, meanings for "digital"?


Digital has multiple meanings but none of them is commonly used as "countable number of states". If you want to know what a specific term means, it's generally a good idea to look it up.

  1. https://en.wikipedia.org/wiki/Digital
  2. https://www.merriam-webster.com/dictionary/digital
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    $\begingroup$ I'd argue that the broad comment discussion in my question post proves that it's not a simple matter of an opener passage in Wikipedia (which I already searched long before the post). If for anything we define "discrete" we define "two or more possible states", I'd assume that it is plausible to say that a digital system is a system with countable or "finite" (digital) number of states. $\endgroup$
    – yaraklis
    Mar 19, 2022 at 20:22
  • $\begingroup$ You can define digital for yourself anyway you like, but as long as you are the only one using the word in this way, any communication with other people will be challenging. By your definition a simple mechanical light switch is "digital". If you call this a "digital light switch" you'll end up a with a lot of confusion. Look, language just is this way: Terms get defined more by common use and habit then by logistical consistency. While there are a lot of discussion in the comments, none of them include your specific definition $\endgroup$
    – Hilmar
    Mar 21, 2022 at 11:28

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