There are many Latin words in English that contain -ae-, including proper names in biology (Archaea, Rosaceae), generic scientific terms (larvae, medusae), Church Latin (Summa Theologiae) and more "common" words such as formulae, curriculum vitae and so on.

I almost always hear these pronounced with /eɪ/, but it looks like this pronunciation is not listed in the dictionaries. For example, formulae only has the /ˈfɔːrmjʊliː/ pronunciation, and curriculum vitae has /ˈviːtaɪ/.

Shouldn't all these pronunciations at least be consistent in the dictionaries? And is there a reason why the dictionaries won't record the /eɪ/ pronunciation?

  • 4
    People actually use them in practice (probably more commonly than their alternatives, at least as far as Latinate feminine plurals in -ae are concerned), so yes, dictionaries ought to record them as well – that is, after all, their purpose. As for being consistent… good luck with that. Aug 27, 2021 at 13:03
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    There is no consistency in English spelling, and this is a nice example.
    – jlawler
    Aug 27, 2021 at 13:38
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    One word where dictionaries do tend to list the /eɪ/ variant is vertebrae – this is also the one such word that I have never in my life heard any native speaker pronounce with /iː/. With most others, there’s vacillation, but in this one, the /eɪ/ variant seems to have won out entirely (though dictionaries still put it second). Aug 27, 2021 at 15:46
  • @JanusBahsJacquet It sounds odd to me as a modern native speaker, but Gilbert and Sullivan specifically require an /i/ in that word: "for he nodded his head and kissed his hand and whistled an air did he / as the sabre true cut cleanly through his cervical vertebrae". I'm not sure if this was an affected pronunciation or standard at the time of writing.
    – Draconis
    Aug 27, 2021 at 19:34
  • Thanks @JanusBahsJacquet, I haven't thought of vertebrae! Aug 28, 2021 at 21:12

2 Answers 2


The traditional English pronunciation of the digraph “ae” is /i:/, as in Caesar, encyclopaedia (US: “e”), haematoma (US: “e”), paedophilia (US: “e”) and lots more.

The (historically) correct pronunciation of Latin “ae” is /aj/, and one hears this occasionally in the English rendering of non-assimilated or partially assimilated borrowings like “larvae”, but there is no good reason for it. English is not Latin.

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    This doesn’t address the crux of the question, namely why the variant /eɪ/ for the Latinate plural/genitive feminine ending is virtually absent from dictionaries. They all list /iː/ (which is becoming less and less common) and sometimes /aɪ/ (which is and has always been pretentious), but almost entirely ignore /eɪ/, despite the fact that this is by far the most commonly heard variant (at least in AmE). Aug 27, 2021 at 15:53
  • Thanks @JanusBahsJacquet, do you think it is actually correct to pronounce formulae as /ˈfɔːrmjʊleɪ/ then since it is not listed in dictionaries? Aug 28, 2021 at 21:18
  • @AleciaKBeasley Formulae is probably one of the words where /eɪ/ is rarer than /iː/ (and perhaps even /aɪ/), but I have heard it, and I don’t think it makes sense to consider it ‘incorrect’. Aug 28, 2021 at 22:23
  • I hear this "correct aj" repeated everywhere, but wasn't it the case manly in the +-times of Plautus. The orthography changed for a reason and even wiktionary writes /ˈkae̯.sar/, [ˈkäe̯s̠äɾ]. Aug 29, 2021 at 11:47
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    @VladimirF The finer details are lost to time (we don’t know if it was [ae̯] or [äɪ] or [ɑɨ] specifically at any given point, because we don’t have recordings), but whatever the exact pronunciation, it was the phoneme /aj/, whose closest English equivalent is undoubtedly /aɪ/, not /eɪ/ or /iː/. Whether you write the Latin phoneme as /aj/, /ai/ or /ae̯/ is just a matter of choice and doesn’t really matter. Aug 30, 2021 at 19:05

This article is about what you asked. Take a notice to a part about professor A. D. Godley: https://en.wikipedia.org/wiki/Traditional_English_pronunciation_of_Latin#Vowel_alone

  • It looks like that note is about the pronunciation of in words like circa*/*circā (correct me if I'm wrong!) and not about -ae. Aug 28, 2021 at 21:22
  • Yes. You are right. I did a split of the upper chart and part about A. D. Godley without re-read of this article. But there are another explanations: the subcategory named 'History' consist information about the vowels' evolution and there are those stages [eː > ei > eɪ] at 1800-2020 and [ɛː > eː] (and possibly > [iː], because I didn't get anything about [iː] for æ/ae, but for Late Latin there is ae /ɛ/, and there is lengthening of [ɛ] to [ɛː] in Middle English in some circumstances). Another explanation lies among English dialectal features, e.g. pane-pain merger. Or maybe in your area...
    – T1nts
    Aug 29, 2021 at 5:28
  • ...happens something like in Lithuanian, where /ai/ in some circumstances sounds as /ei/ (e.g. kvaila).
    – T1nts
    Aug 29, 2021 at 5:30

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