I'm writing my thesis and I added a glossary at the start with the more complex terms and their definitions.

The definitions usually come from scientific papers. My question is: should I cite those papers if I use their definition? (Even though I'd say a definition is something that is global.)

  • Which field is this about?
    – Tommi
    Oct 9, 2018 at 12:49

2 Answers 2


If you use something from another paper, then you should cite it. Make that a general rule. There are a number of reasons for it, only one of which is to avoid a charge of plagiarism when someone notices that they have "seen that before."

The other, perhaps primary, reason is that scholars want to know how a paper is situated within the scientific/mathematical literature and if previous work isn't cited it is difficult or impossible to do so. A future reader of your work may want to know where else this definition appears and what its history is. Citations make this possible.

However, for things that have become common knowledge, such as the definition of the derivative (math) or ph (chemistry) you don't need to give definitions as you can expect that they are known to every scholar in the field. But you probably wouldn't repeat those definitions in the first place unless you were doing a comparative history study of some kind, in which case you would cite the original sources.

Don't quote or paraphrase the work of others without citation.

  • Definitions in a glossary are nearly always common knowledge, so the answer would be that citations are not necessary.
    – Louic
    Oct 9, 2018 at 16:22
  • @louic, if the papers are at all recent or in any way obscure, then the definitions are possibly not common knowledge. Mathematicians, for example, are happy to define new things. It is only the OPs reputation on the line.
    – Buffy
    Oct 9, 2018 at 16:27
  • Sure there are always exceptions, but answer this: have you ever seen a thesis with citations in the glossary? In practice the definitions are nearly always well known concepts. If not they will be further discussed in the thesis (otherwise there is no point adding them to the glossary in the first place), and the sources can be discussed and cited there.
    – Louic
    Oct 9, 2018 at 16:33
  • @louic, my own thesis, I guess. I worked in a pretty obscure area that was known to only a few living mathematicians at the time. It was necessary to give background on the work and to cite my predecessors. It seems to me to be a mistake to make subtle distinctions to general rules that can only harm you when someone objects. If you use it, cite it. Keep it simple.
    – Buffy
    Oct 9, 2018 at 16:39
  • Fair enough. If the definitions are not common knowledge the papers should be cited (as my answer also implies).
    – Louic
    Oct 9, 2018 at 16:49

No, it is very uncommon to cite papers for copying a definition. Why? Because a definition is (by definition) accepted as a word for daily use (albeit possibly in a small field). Secondly, it is usually difficult to know whether the paper you are citing is actually the source of the definition or if they copied it from another paper or conference (possibly partly or using different words).

Citations in your glossary would be comparable to citing old English literature for every uncommon word you use in your thesis. This is no different for "scientific" words that happen to end up in your glossary.

Of course, if the definition is controversial, particularly important for the subject of your thesis, or requires further explanation, you can give details elsewhere in your thesis and cite the relevant papers there.

  • 1
    Are you suggesting it is okay to take text from a paper and include that text in a thesis without indicating that the text is from the paper? That sounds like plagiarism to me.
    – user2768
    Oct 9, 2018 at 14:37
  • 1
    No that is not what I am suggesting. I am suggesting taking definitions from a paper, where I have defined definitions as common knowledge. Plagiarism is copying text and presenting it as your own. A definition list is (by definition) not presented as if it is your own work.
    – Louic
    Oct 9, 2018 at 16:19

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