Will no one rid me of these tiresome Latin plurals?

The English language has inherited many scientifc words from Latin: a spectrum, an index, a torus, a formula. Then which plural forms should we use: the Latin plurals two spectra, two indices, two tori, two formulae? Or the English plurals two spectrums, two indexes, two toruses, two formulas? The Latin and the English plurals of these words are both considered correct, but the Latin plurals are more widespread. I will nevertheless argue that using Latin plurals is impractical and illogical, and should often be avoided.


The main argument against Latin plurals is that irregular grammar makes a language more difficult. And the main argument in favour of irregular grammar is that it contributes to the beauty and richness of a language, and reflects its history. For a global technical idiom such as scientific English, this esthetic argument carries little weight. And the irregularities are particularly detrimental, because most users are not native English speakers, and have to learn the idiom as adults.

Moreover, there is something basically illogical in using Latin plurals. The plural form is a type of declension, but in the Latin language there are also declensions for cases. If these spectra are interesting, should we study the features of these spectrorum? Declensions in English are much simpler, but there is still a possessive case. When talking about these spectra’s features, I am adding an English possessive ending to a Latin nominative plural. It would be more logical to only borrow nominative singulars from Latin, and to let them follow English grammar, including English plurals.

Still, there are cases when Latin plurals are hard to renounce:

• The English plural may be unwieldy. For example, genuses and toruses are ugly, but genera and tori sound better.
• The English plural may coincide with a verb, and the Latin plural may lift the ambiguity. For example, if we take the plural of index to be indexes rather than indices, then the word indexes is both a noun and a verb. Of course, noun/verb ambiguities are a major bug of the English language, and Latin plurals can only help in a few cases.

To conclude, here are examples of Latin plurals that should surely be eliminated:

• minima \(\to\) minimums
• spectra \(\to\) spectrums
• formulae \(\to\) formulas
• tetrahedra \(\to\) tetrahedrons
• ansätze \(\to\) ansatzes (this one is German, not Latin)

And examples of Latin plurals that we might want to spare:

• indices / indexes?
• genera / genuses?
• tori / toruses?
• matrices / matrixes?

(Notice that words such as analysis \(\to\) analyses are of Greek, not Latin origin. The English rule for the plurals of words in -is was coopted from the Greek language, so there is no alternative plural in such cases.)