I was wondering how the word Cactaceae, which is the botanical taxon for the Cactus family, is pronounced. I searched for "Cactaceae pronunciation" and found the following pronunciations:



It seemed a bit strange that the second a is pronounced as see rather than mate so I searched on an found the Merriam-Webster pronunciation, which reads:


If I'm not mistaken, this is to be parsed as


So, which one's the correct pronunciation? I don't suppose a lot of people have ever uttered this word out loud, but I have an upcoming presentation in English and will be using this word a lot.

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  • @JoeDark: I have linked that page in my question. The way the man pronounces the word differs from Merriam-Webster's prescription. Hence the question. – Armen Ծիրունյան Dec 28 '14 at 15:39
  • @ Armen Ծիրունյան Just pick whichever version you prefer. I'm quite sure that everyone will think that your pronounciation is correct. – Joe Dark Dec 28 '14 at 15:44
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    @JoeDark Your comments are uniformly anti-useful here: they do nothing to provide notational direction or realistic advice. I advise you to delete them. – tchrist Dec 28 '14 at 16:09
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    The pronunciation in Joe's link by Howjsay is correct and traditional, especially /kækˈteɪsii/. I would stick with that. The ʃ is probably excusable. I don't understand why some people would pronouce -ae as /eɪ/: what precedent is there? – Cerberus_Reinstate_Monica Dec 28 '14 at 23:55

You are being confused because of the misleadingly nonstandard pronunciation symbols being inexcusably thrust upon you by Merriam-Webster. It it in your best interest to ignore utterly any source whose pronunciation fails to use standard IPA.

Turning to a dictionary that does employ standard notation, the related word cactaceous, meaning per the OED:

Belonging to the old genus Cactus; or to the natural order Cactaceæ.

is normally pronounced /kækˈteɪʃəs/ according to that same source.

That tells you how Cactaceae starts out, but leaves you a bit in the dark about how it finishes up. Most of the remaining mystery lies in how the ‑aceae suffix can be pronounced several ways, depending on one’s formative education and personal predilection.

So for example, although I myself — and I am hardly alone in this — pronounce the word Cactaceae as /kækˈteɪʃiɑɪ/, other people are more apt to say /kækˈteɪʃieɪ/ or /kækˈteɪʃeɪ/ there instead.

I have never heard /kækˈteɪʃi/ but can imagine it existing. Probably very few still pronounce it as if it were Classical Latin, so /kɑkˈtɑkiɑɪ/ or even with some small effort to preserve the diphthong, /kɑkˈtɑkiɑe/.

Mostly what is happening is that the /si/ becomes (as it so often does) /ʃi/ there; think of spacious and many other such words.

I recommend to you the Wikipedia article on the ‘traditional’ English pronunciation of Latin. This is still true in general, but studious specialists of a younger generation sometimes do more in the way of maintaining the Latin diphthongs than our elders were wont to do.


As John Lawler astutely notes in comments, it may be important to preserve an unpalatalized /s/ instead of using /ʃ/ for the ‑aceae suffix in some contexts, because that suffix is a clear marker to botanists that one is referring to a plant taxon at the Family level.

That would make it end in /esie/ phonemically — or, with explicit phonetic diphthongs and glides as always occurs in English, in [eɪsijeɪ]. It really depends on how fancy you are getting with your notation, because those are the same thing.

The Anglophone botanists I know indeed use a simple /e/ (phonetic [eɪ]) for ae. I may hear the [ɑɪ] variant mainly from people who have spent more time with school-Latin than with actual English-speaking botanists. :)

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    When I used to hang around with botanists (I was on a couple PhD committees), they pronounced botanic Latin using standard English Latin pronunciation; i.e, /kæk'tesiye/ for Cactaceae. The suffixes are important because they can mark the taxonomic level (-aceae indicates that it's a Family, for instance, not an Order or a Genus). A cactus specialist might well palatalize it to /kæk'teʃiye/, or if the taxon is not at issue, might just use an old label like /kæk'teʃəs/. But for most people who aren't biologists and don't play them on TV, /kæk'tesiye/ is the way to go. – John Lawler Dec 28 '14 at 16:12
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    @JohnLawler That sounds about right. The palatalization feels a bit lazy. I’m not sure that your ʃiye is different in realization from my ʃieɪ: you mark one glide and I mark another, but it seems to me that both happen at the phonetic level simply because of how those phonemes wind up getting said in real English. – tchrist Dec 28 '14 at 16:16
  • Oh, by the way, if /kæk'tesiye/ looks weird to you, don't worry; it's just the American English phonemic alphabet, from Kenyon and Knott's Pronouncing Dictionary of American English. More details here. @tchrist: yes, I think they're the same. Phonemics overgeneralizes. – John Lawler Dec 28 '14 at 16:18
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    @JohnLawler Oh, I’m used to your notation by now, although that’s probably an important addendum for folks expecting /j/ there per IPA. – tchrist Dec 28 '14 at 16:19

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