Is it true to say that in English always when word starts with "P+S", the the letter p is dropped out of pronunciation and become silent?

I know about some words which behave like that, such as psychology and psychiatry. But I'm not sure if there are no exceptions, or maybe these words that I mentioned are exception.

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    I'm not aware of any words where an initial ps doesn't drop the p in English pronunciation. I also believe that all such words came into English from Greek roots, and were spelled with an initial Ψ. Nov 17, 2017 at 13:10
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    I was going to endorse @Jeff's comment, but checking the full subscription-only online OED it only took a few seconds to turn up pschent - (Ancient History) A headdress of ancient Egypt, combining the white crown of Upper Egypt with the red crown of Lower Egypt, used after the formation of the State (c 3000 b.c.). For all practical purposes, though, you could reasonably ignore "words" like that, since almost no native speakers would know them anyway (and even if they did, they might well "mispronounce" it by discarding the /p/ ! :) Nov 17, 2017 at 14:44
  • @FumbleFingers - It's quite likely that even that word got into English via Greek. But I'll admit that I wasn't considering any sort of obscure words like that... :) Nov 17, 2017 at 15:48
  • Before reading your last comment I'd have been quite prepared to believe that all English words starting with ps came from Greek. But since I still had the OED page open in my browser, I just checked the very next entry... pselaphognath (Any of various minute millipedes comprising the subclass Pselaphognatha, having a soft integument bearing tufts and rows of bristles). Apparently that's from latin. Nov 17, 2017 at 18:43

1 Answer 1


Yes, the ⟨p⟩ is always silent in words that start with ⟨ps⟩. The cluster /ps-/ is not a legit onset cluster in English because it violates the Phonotactics constraints of English.

Every language has a fixed set of rules called Phonotactics or Phonotactic rules/constraints that determine the permissible sequences of sounds. In simple words, Phonotactics studies what sounds go together, and where can they be found in a word.

For example, the sequence /pn-/ is allowed in Greek, but not in English. That's why the P in the word pneumonia is pronounced in Greek, but silent in English because English doesn't allow a cluster of PLOSIVE (/p t k/) + NASAL (/m n ŋ/) in the same syllable.

According to English Phonotactics constraints, English cannot have an onset cluster beginning with a plosive /p t k/ followed by a fricative /s z ʃ ʒ/. Therefore, the ⟨p⟩ in psychology and psychiatry is silent. Similarly, the ⟨t⟩ in the word tsunami is also silent in English.

Also note that the plosive is only silent when it's in the onset and precedes a fricative in the same syllable. In the syllable coda, however, the sequence 'Plosive + Fricative' is allowed.

/slashes/ represent phonemes (sounds) while ⟨angled brackets⟩ represent spelling.

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