Latin in Scientific Writing: When do you use it?

If you have read a scientific article or scientific publication before, it is highly likely that you have read some Latin terms. Latin in Scientific Writing is a relatively common practice. Many English words come from Latin and many of the terms we use today still follow the rules of Latin. Sometimes we even see Latin terms and phrases such as cf., et al. and in vivo. But when and how do you use Latin?


For scientific terms in English that come from Latin, many of the plurals look a bit odd. Even more strange is some of the singular nouns, especially when we usually use the plural. Why is this? It’s because they still follow the original singular/plural rules in Latin – and there are a lot! Here are the most common:

  1. Wordings ending with -a become -ae or -ata
    1. larva -> larvae
    2. alga -> algae
    3. stoma -> stomata
    4. carcinoma -> carcinomata (sometimes also “carcinomas”)
    5. adenoma -> adenomata (sometimes also “adenomas”)
  2. Words ending with -on become -ia
    1. mitochondrion -> mitochondria
    2. phenomenon -> phenomena
    3. criterion -> criteria
  3. Words ending with -um become -a
    1. bacterium -> bacteria
    2. datum -> data
  4. Words ending with -us become -i
    1. locus -> loci
    2. nucleus -> nuclei
    3. fungus -> fungi
  5. Words ending with -us become -uses
    1. nucleus -> nucleuses
    2. sinus -> sinuses
    3. virus -> viruses
  6. Words ending with -es stay the same
    1. facies -> facies
    2. series -> series
    3. species -> species
  7. Words ending with -is become -es
    1. hypothesis -> hypothesis
    2. diagnosis -> diagnoses
    3. analysis -> analyses
  8. Words ending with -ix/-ex become -ices
    1. cortex -> cortices
    2. apex -> apices
    3. index -> indicies
    4. cervix -> cervices
    5. matrix -> matrices
    6. appendix -> appendices
  9. Words ending with -is become -ides or -ises
    1. arthritis -> arthritides
    2. phlebitis -> phlebitides
    3. hepatitis -> hepetitdes/heptitises
    4. neuritis -> neuritides/neuritises

That is really confusing! Why??? Well, part of it is that Latin is a complex language. Another reason is that some “dialects” of Scientific English (I’m looking at you, American English) has decided that Latin plurals are too complex and decided that some of the words should follow English singular/plural rules, which hasn’t really helped much.

Latin Phrases in Scientific Writing

While there are many Latin phrases and abbreviations that you may find in Scientific Writing, here are the most common ones:

  • i.e.
    • id est, ‘in other words, that is’
  • e.g.
    • exempli gratia, ‘for example’
  • viz.
    • videlicet, ‘namely’
  • vs.
    • versus, against (contrast)
  • etc.
    • et cetera, ‘and so on’
    • Ideally, don’t use in scientific writing
  • N.B. -> notāre bene, ‘note well’
    • Always capitalised!!!!
  • et al.
    • et alii, ‘and others’
  • cf.
    • conferre, ‘compare with’
  • q.v.
    • quod vide, ‘see/refer to’
  • in situ
    • in its original place
  • in vivo
    • in a living body (not under laboratory conditions)
  • in vitro
    • in an artificial environment

That’s great, but when do I use them?

Generally, it is alright to use a Latin phrase if it is:

  1. Common – don’t go searching for obscure ones. Stick to the list above. Also, make sure it is common in your discipline. Computer scientists almost never use in vivo because they have very little in vivo research. However, in silica (meaning computer-simulated) is very common, so it is fine to use that one.
  2. Useful – if the phrase helps you save space or explain a point more accurately than an equivalent English phrase, use the Latin one.

If the phrase does not fulfil both of these criteria, do not use it! Remember we are supposed to be making our article easy to understand, not harder. If a reader has to stop reading an article to find out what a specific term in Latin means, then the Latin should not have been used.

Want to learn more about Scientific English? You can find some more articles here.

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Interested in learning more about Scientific English? You can read a brief post on the History and Use of Scientific English here. More posts on Scientific English are available on the Scientific English page.

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