As shown in the Wiktionary:


From Proto-Indo-European *sriges-, *sriHges-.

But I can't find the clue to this sound change on Wikipedia, which concludes that PIE*bʰ, *dʰ, *gʷʰ will become L. f-, when they are "At the beginning of a word".

  • I'm not sure we know more details about this phonological process; in many cases, all we know is that it happened. I wouldn't know about this change in particular.
    – Cerberus
    Commented Apr 25, 2013 at 14:28
  • @Cerberus "Know" is a strong word to use for linguistic reconstruction. Commented Dec 24, 2021 at 19:10
  • The answers presume the reconstruction rather than explaining how it came to be. It would be helpful to have examples from other IE languages. Searching for these (from say Nordic, Iranian, or Indic languages) is how I came across this page, but it hasn't offered any more information than one could get from reading the etymology of "frigid" and using some logic & guesswork. Since someone reconstructed the PIE root, surely their justification exists somewhere. Otherwise it seems safer to me to assume the root word doesn't actually go back as far as PIE culture. Commented Dec 24, 2021 at 19:19

2 Answers 2


Word-initial PIE *sr- > L. fr-

L. frigus, cf. G. ῥῖγος

Word-medial PIE *-sr- > L. -br-

L. funebris, cf. L. funus, funeris

The intermediate stage was PIE *sr > PIt. *θr.

(Baldi 1999: 284; Leummann 1977, §194, §207; Sihler 1995, §225.2: Weiss 2009/2011: 163)


I don't think we ever know for sure how a sound change happens. We can deduce what changes have happened (and sometimes experience what changes are happening), and we can certainly conjecture about the phonetic processes involved, but we can never really answer how (or why) questions.

Here, the obvious conjecture is that in that context, the fricative /s/ came to be replaced by a different fricative /f/. In other places the sequence became /ʃr/ or /str/, suggesting that it is often found to be awkward. I also notice that when I pronounce /sr/ I have a tendency to project my lower lip. If I happen to protrude my upper lip a bit, it can become /sfr/ (actually /sφr/, with a bilabial fricative).

Notice that the other examples you give are difficult to understand unless you assume that they went through a fricative stage such as /β/, /ð/ or /ɣ/; then the probable process would again be substitution of the different fricative /f/.

You can see a similar process at work currently in dialects of English where /θ/ (as in think) appears as /f/.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.