What is the difference between scheme and schema? Where do you use one and not the other?


  1. a diagram, plan, or scheme. Synonyms: outline, framework, model.
  2. an underlying organizational pattern or structure; conceptual framework: A schema provides the basis by which someone relates to the events he or she experiences.
  3. (in Kantian epistemology) a concept, similar to a universal but limited to phenomenal knowledge, by which an object of knowledge or an idea of pure reason may be apprehended.


  1. a plan, design, or program of action to be followed; project.
  2. an underhand plot; intrigue.
  3. a visionary or impractical project.
  4. a body or system of related doctrines, theories, etc.: a scheme of philosophy.
  5. any system of correlated things, parts, etc., or the manner of its arrangement.

The funny thing is that the dictionary entry of schema refers to scheme. Does that mean they can be used interchangeably? If not, can someone please give practical examples of how and when to use one and when the other?

  • Hello znq. I'm voting to close your question as General Reference, because the difference is easily found by looking up the dictionary (I just did it). If there is something more you want to ask about this, feel free to edit your question and add/modify information. :) – Alenanno Sep 5 '11 at 11:17
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    There's one thing finding an answer in a dictionary and another thing understanding it, especially for a non native English speaker. If that is the general rule, then pretty much anything can be found in a dictionary (or somewhere else on the Internet) and we can close down all the StackExchange sites. – znq Sep 5 '11 at 11:20
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    Have you tried looking up the dictionary? What differs is just one thing. If you still have doubts, I'll post an answer. – Alenanno Sep 5 '11 at 11:55
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    Alenanno, I updated my question with more information. However, what is still unclear to me is when to use one or the other in practice. The dictionary description is, for my taste, very abstract and hard to grasp. – znq Sep 5 '11 at 12:42

The key here is the third definition of Schema, that of Kant; if he's not the guy that re-introduced the old Latin form of the word, then he's certainly the guy who popularized it, and brought it to such common usage in our modern language. Etymology Online and Google Ngrams both place its entry into English at about the same time as Kant's work; Webster's and a few other dictionaries place it about 60 or 70 years later. The difference is probably due to the lack of popularity, or common usage as the term slowly worked its way into standard English.

In any event, Kant's idea of a "schema", when translated to our current understanding, is something like "the fundamental, intuitive ordering principle which people use to establish categories, whether mental, sensory, or 'transcendental'." For instance, the category of "quantity" must be ordered by number; thus, "number" is the "schema" of the mental category we understand as "quantity".

A "scheme", however, is essentially a plan or idea that one implements towards a certain goal; but there are exceptions, as when we say "color scheme". If we all spoke more strictly, this would probably be 'color schema", but in fact, "scheme" and "schema" are very, very close words, both derived from one Ancient Latin/Greek word, and so in casual usage can seem interchangeable to folks like you and me. Since scientists no longer rely on "schema" as an important term of scientific practice, or debate, it has lost the institutional rigor it once enjoyed and is now slowly morphing together with "scheme".

Except for one instance: schema is never a verb, and can only be a noun. So that is where the confusion comes in; "schema" used to be a rigorously debated scientific term, part of the "meta-discussion" that surrounded early science, but that era has, for all intents and purposes, long disappeared. Now lacking any formal body of usage, "schema" mostly just hovers on the edge of our standard vocabulary until somebody needs a clear-cut noun for "abstract principle of ordering", or some such.

But often as not, people are lazy enough to just drop the "a" and use the word as "scheme", so.....

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    Beautiful description of differences. I have studied psychology myself, and it pains me to see that these two words can even be confused with one another. – Rachel Sep 5 '11 at 19:06
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    Came here to see if I should rename this class I'm building to "ColourSchema".. did not disappoint :) – Inversus Apr 15 '15 at 18:58
  • Now I'm wondering if the first parts of URLs should be called schemas instead of schemes. – Steve Moser Mar 14 '16 at 19:42

Since you couldn't find it, I'll say that the Oxford Advanced Learner's Dictionary lists Schema as a technical word, while it says nothing for Scheme regarding its usage.

I'd say this is an important difference, considering that the meanings are quite similar; although there's also the fact that Schema also refers to diagrams/models, while Scheme doesn't.


I would add that if you don't know exactly what you're doing, or if you're not talking about highly jargon-ized field (like psychology), you should stick with "scheme", lest people think of you poorly.


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