I'm working with someone who uses noncompatible often in correspondence. The confusion may be due to English being a second language for them.

I think they should be using incompatible instead. Is that correct?

It is better to not show those user profiles to noncompatible individuals.

Does the answer change if we are talking about software?

It is better to not use software that is noncompatible with outdated hardware.

  • 2
    Noncompatible is vanishingly rare by comparison with incompatible. I think to the extent it's "properly" used, it tends to be more in technical contexts where one or a few instances of something aren't compatible with a more broad-based system. OP's colleague probably shouldn't use it of mutually incompatible individuals, for example. Jan 22 '12 at 16:07
  • 1
    In software, incompatible is always used. Noncompatible would be considered very obtuse. Jan 22 '12 at 17:48
  • The real issue is not between incompatible and non-compatible. Since the latter is clearly out of favor, the correct alternatives are incompatible and not compatible. Note that they do not mean the same.
    – Kris
    Jan 23 '12 at 10:11

English speakers prefer "incompatible" over "noncompatible" by an overwhelming majority (Google Ngram). "Noncompatible" does appear in some dictionaries, though not many. So it exists, but it seems to be extremely non-standard or extremely specialized, or both.

  • I see @FumbleFingers posted essentially the same thing as a comment while I was typing this answer :) Jan 22 '12 at 16:15
  • I did notice the difference in search queries, hmm. I just wanted to make sure incompatible is the right choice before making lots of edits to our documents.
    – Dreamling
    Jan 22 '12 at 16:49
  • The words are not synonyms or analogous in the first place.
    – Kris
    Jan 4 '14 at 6:05
  • You have cited the Wiktionary entry: non-compatible = not compatible, not incompatible.
    – Kris
    Jan 4 '14 at 6:07

Most Indians use noncompatible in place of incompatible mainly due to direct translation of what they think and say in their own languages. As long as the work conveys to the other party what it should there is no problem in using either of them.

  • Welcome to EL&U. We appreciate your input. :) Jan 4 '14 at 6:08
  • As an Indian, I'm not sure about the "most Indians" part...
    – user1635
    Jan 4 '14 at 16:53

Incompatible is the correct usage. Noncompatible is not a word normally used in communication, although it may exist. It sounds like a piece of business-speak - "noncompatible individuals" sounds like a way of saying "people who don't fit".


Approaching this problem from a vantage point of logic, (rather than a proper rule), the fault with either construction is that it makes attribution rather than withholds attribution. Since what's at issue is a property lacked rather than a property outright, it's preferable to opt for the term "isn't compatible" rather than "is incompatible" or "is noncompatible".

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