Dipthong.

Or either that or diphthong, one.

Corrected.

The only excuse for missing that one is that for the last three days I’ve been writing articles on Old English literature and, as a result, have been ignoring spell check.

[From the Atlantic article:]

So why, in the end, “diphthong? Which is also to ask: Why not “hornswoggle”?

“That was a tough call,” McCagg concedes. But “that silent ‘h’ in diphthong made all the difference.”

Silent ‘h’? I pronounce it as it’s written (DIF-thong), it’s not a word I often have occasion to use, so I’ve not heard many other people say it. Are there other ways to pronounce it?

(I imagine it’s something of a bear-trap for anyone who has trouble pronouncing ‘th’.)

I pronounce it like you, Dr F, but I am aware that the other pronunciation is fairly common.

It’s commonly pronounced /’dɪpθɔːŋ/, even by Seth Lerer in the Great Courses: History of English series.

Collins gives both pronunciations, but firstly ˈdɪfθɒŋ.

A quick straw poll of my two work colleagues yields one of each pronunciation. I guess the ‘phth’ combination is fairly rare - I can only think of diphtheria, phthisis and naphthalene off hand, none of them exactly the stuff of everyday conversation. And (come to think of it) I’m fairly sure that I’ve heard diphtheria and naphthalene pronounced as if the first h wasn’t there. I don’t think I’ve ever heard anyone actually pronounce phthisis (I only know it as being fairly common on 19th century death certificates I’ve read doing family tree research).

Yeah, most people in my experience say “diptheria” and “napthalene”.  And in “phenolphthalein” the entire ph tends to be left out and people just say “phenolthalein”.  Never heard that one with the /p/, though.

edited for typo

Dip-thong is the pronunciation I’ve always used. There’s a triphthong out there too which might dispute it;s brother’s title.

I don’t think I’v ever had to say “diphtheria” out loud (thank goodness!), so I can’t tell how I’d have said it - but ( pace Dr. T) I can’t help saying “phenolphthalein” with the clearest “f” sound my aged teeth will allow. My training as a chemist makes me do it (with a soft “th”, too). Same goes for “phthalic acid”. I suppose non-chemists don’t get to say those words all that often.

More phthower to you!

Phthank you

Ophthalmology.

I pronounce the f in all of these examples, except op-thalmology.  Dunno why.

I pronounce ophthalmology with an F, consistent with my pronunciation of other PHTH words, but I’ve since thought of an exception (in my case).

Phthalo green is a dark slightly bluish green artist’s paint colour. (Wikipedia tells me that the pigment is Phthalocyanine Green G.) I pronounce it as ‘thalo’ because that’s the way my art teacher pronounced it. (My younger daughter, on the other hand says ‘phalo’, because she has trouble with TH.)

There’s a surprising number of PHTH words out there once you start thinking about them.