I have discussed the usefulness of acronyms and initialisms and the importance of finding the best place to introduce them. However, it is also useful to know when not to use an acronym or initialism. After all, they are optional – an author doesn’t have to use one if there is no need for it. There are many reasons not to use an acronym or initialism.

When the term is not used again

Very often, I see a writer introducing acronyms and initialisms for all kinds of terms, even if they are never used again in their paper. I feel this is unnecessary. An acronym or initialism is a shortened version of a term created so that later mentions of that term are not as long, in order to reduce the length of a text or for ease of reading. If it is not mentioned again, then introducing the acronym or initialism is unnecessary, and even adds to the length. Here’s an example of some unnecessary initialisms:

With initialisms: “To solve multiphysics problems, researchers have developed finite-difference time-domain (FDTD), finite-element time-domain (FETD), and boundary-element time-domain (BETD) numerical methods.”

Unfortunately, in this paper, ‘finite-difference time-domain’, ‘finite-element time-domain’, and ‘boundary-element time-domain’ are not mentioned again, and neither are ‘FDTD’, ‘FETD’, and ‘BETD’. These terms are very similar and easily confused. Hence, these initialisms can be removed completely:

Without initialisms: “To solve multiphysics problems, researchers have developed finite-difference time-domain, finite-element time-domain, and boundary-element time-domain numerical methods.”

Without the initialisms, I can restructure the sentence to make it even shorter:

Simplified: “To solve multiphysics problems, researchers have developed finite-difference, finite-element, and boundary-element time-domain numerical methods.”

However, this last case obscures how these are three distinct methods, instead suggesting one general method in three forms, and it is not clear which one is described as “time-domain”, so this approach may be a step too far. Nevertheless, you can see that introducing unnecessary initialisms only made the text longer, not shorter.

Despite this, there are some occasions where a writer may wish to define an acronym or initialism that isn’t used again, to educate the reader on what a common acronym or initialism means or to clarify that something is commonly known by an acronym or initialism. This will most often apply to the proper names of programs, software, and institutions. For example:

  • Correct: “Shaking table tests were conducted at the National Center for Research on Earthquake Engineering (NCREE).”
  • Correct: “The Navier–Stokes equations are solved using the SIMPLEC algorithm (Semi-Implicit Method for Pressure Linked Equations-Consistent).”

When the term is rarely used or very small

Furthermore, if an acronym or initialism is only used once or twice in the paper, then it may not be necessary to introduce it at all. Let’s look again at the thesis’s Chapter 5 example above. The two sentences are from the beginning and end sections of the chapter:

  • “This chapter shall concentrate on using the modified Chebyshev expansion of the acoustic wave propagator to computationally model the propagation of sound from the noise source and its scattering around the barrier.”
  • “In this chapter, an innovative wave-trapping noise barrier was modelled and compared to equivalent traditional noise barriers, using the modified Chebyshev expansion of the acoustic wave propagator to propagate noise around them.”

Using the full term ‘acoustic wave propagator’ in the second sentence doesn’t make it much longer than using the initialism ‘AWP’ instead. In terms of word count, the chapter is only two words shorter compared to the case using the initialism (as ‘AWP’ is a word). If each mention of an initialism is very far apart, then the reader could forget what it means.

An acronym or initialism is also created to avoid very long or repetitious terms. A reader would not want to read dozens of instances of ‘boundary-element time domain’, but ‘BETD’ is much easier to read. However, suppose we only have ‘time domain’. It has only three syllables and two words, and is relatively short. This could be written as an initialism, ‘TD’, which has two syllables and counts as one word. ‘TD’ is not significantly shorter than ‘time domain’, so using this initialism won’t significantly reduce word count or reading time.

When the term may be confused

As an editor at Uni-edit, I often encounter mistyped acronyms and initialisms. When typing, it is easy to switch two letters or press an incorrect letter, and a spell-checker program often won’t detect this change (as an acronym or initialism usually doesn’t look like a real word anyway). A reader can also misread one letter as another, or misunderstand a sentence and wonder if the author has written something incorrectly. For example, with ‘finite-difference time-domain (FDTD), finite-element time-domain (FETD), and boundary-element time-domain (BETD)’, it is easy to mistype or misread FETD as FDTD and ‘TD’ might be mistaken or thought to be a typographic error for ‘2D’ or ‘FD’ (that is, ‘finite-difference’). You can see how very initialisms can be ambiguous.

Furthermore, some acronyms and initialisms are identical. For example, hardened cement paste is initialized as ‘hcp’ and a hexagonal close-packed crystal lattice is also initialized as ‘hcp’. It is common to see different terms giving identical initials in very different fields, where they are unlikely to be mistaken, but it can occur even in related fields or within a single field. The initialism hcp will be an issue if a paper investigating such materials uses both terms.

Initialisms can also be similar to mathematics. In a paper I recently edited, an author defined a model in terms of its diameter, denoted as D, so it had measurements like 1D, 2D, 4D, and so on. The models discussed however were two-dimensional and three-dimensional, which are commonly written as ‘2D’ and ‘3D’, respectively. You can see how easy it is to confuse 2D and 2D. Wisely, this author chose to write ‘two-dimensional’ and ‘three-dimensional’ as ‘2-D’ and ‘3-D’, with a hyphen between the number and ‘D’, to make them more distinct, and fortunately didn’t use these at all after the model parameters were introduced. To be absolutely certain, however, I wrote these out in full as ‘two-dimensional’ and ‘three-dimensional’, to eliminate ambiguity, as these were not mentioned very often anyway. Thus, it is preferable to use acronyms and initialisms that are not too similar to each other, to limit the risk of error or ambiguity, but this is rarely possible in practice, as they are restricted to the initial letters of the terms used. Therefore, using as few acronyms and initialisms as possible is a good way to limit error and ambiguity.

When the term appears in titles and section headings

In my work, I often see authors introducing their acronyms and initialisms within the titles of their papers. This might be because the first use of a term in the paper appears to be in the title. Alternatively, the author may have wished to include the acronym or initialism as extra information. In some cases, only the acronym or initialism is used in the title. This is generally not recommended by journal guidelines and editors, however. Consider the following paper title:

  • Unnecessary: “Split-region acoustic wave propagator (AWP) and its applications”
    Here, the initials ‘AWP’ are redundant—they do not add anything to the reader’s understanding of what the paper is about, as it is already stated that the paper is about the acoustic wave propagator. Consider an alternative title:
  • Unclear: “Split-region AWP and its applications”
    A potential reader might not know what ‘AWP’ means, and might pass over this paper. Furthermore, a reader who searches online for ‘acoustic wave propagator’ might not find this paper, as the term is not used in the title. Now consider the original title:
  • Clear: “Split-region acoustic wave propagator and its applications”

In this case, a potential reader will know at a glance that the paper covers a new implementation of the acoustic wave propagator. It will also be easier to search for online, and the title appears tidier without unnecessary letters and brackets. As with abstracts, it is therefore best to treat titles as being independent of the main text of a paper, and not to use or introduce an acronym or initialism in the title if there is no need to. Only very well-known acronyms and initialisms, those that have become words, and those that appear on a journal’s list of accepted abbreviations should be used in a paper title. A very long term like the name of a chemical, project, algorithm, or software can also be written as an acronym or initialism to make the title shorter, as long as the meaning is clear and it is a standard name.

In section headings within a paper or chapter, however, it is acceptable to use acronyms and initialisms, but there are some points to keep in mind. First, as with the main text, I don’t recommend using an acronym or initialism in a chapter title or section heading if it has not previously been introduced or explained to the reader, else the reader might not understand what it means or what a section is about. A thesis or book has a table of contents at the front listing all the section headings, so acronyms and initialisms used here might not be known to the reader at first, and it will be harder to look up these topics. For example, consider this chapter title and section heading:

  • Unclear: “Chapter 3: AWP”
  • Unclear: “3.2 1D AWP”

These won’t mean much to a reader just starting to read this chapter. Furthermore, the close sequences of numerals and letters can be confusing, as it doesn’t look like regular writing at first glance. The full names are more legible:

  • Clear: “Chapter 3: Acoustic Wave Propagator”
  • Clear: “3.2 One-dimensional Acoustic Wave Propagator”

Nevertheless, there are good reasons to use acronyms and initialisms in section headings, for the same reasons they are used in standard text—to shorten or simplify the statement. Let’s consider a very long section heading:

  • Clear but long: “3.4 Modified Chebyshev Polynomial Expansion of the One-Dimensional Acoustic Wave Propagator”

In a paper or thesis, this heading could take up two lines of a table of contents or two lines in the main text, making it appear untidy or increasing the length. We can shorten this by using the initialisms:

  • Clear and shorter: “3.4 Modified Chebyshev Polynomial Expansion of the 1D Acoustic Wave Propagator”
  • Clear and shorter: “3.4 Modified Chebyshev Polynomial Expansion of the One-Dimensional AWP”
  • Clear and shorter: “3.4 Modified Chebyshev Polynomial Expansion of the 1D AWP”

These have most likely been introduced to the reader by this point.

On the other hand, there are also good reasons to use full terms in section headings instead of acronyms and initialisms. I discussed earlier how it can be useful to reintroduce the full meaning of an acronym or initialism as a reminder to the reader, but warned that editors and journals might undo these in favor of the standard rule. Therefore, another way to remind the reader of the full meaning is to use it in a section heading, like so:

  • “3.2 One-Dimensional Acoustic Wave Propagator”
  • “To model an acoustic wave as it evolves in time, Pan & Wang developed the AWP approach as an analogy to the quantum wave propagator, which was already in use by quantum physicists.”

Although there is no formal definition of ‘AWP’ here, reusing ‘acoustic wave propagator’ in the section heading effectively reminds the reader of what it means. An editor usually won’t drastically change a section heading or title, so the full term can be preserved here

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