In the Complete Welsh-English/English-Welsh Dictionary the word fy is equivalent to the English my or of me. It also includes the Old Welsh spellings of fyng/fym/fyn. Is the Old Welsh versions a masculine/feminine/neuter or is there something else involved?

1 Answer 1



The alternative spelling here represents the nasalisation that fy causes on the following word, which were sometimes (but far from always) written out in Old Welsh.



Long version

Historically, fy comes from Insular Celtic *men(e) which, as a possessive determiner, would always be unstressed. Unstressed function words have a tendency to become permanently lenited and have their vowels reduced, so *men(e) became *mən and then *vən (/v/ being the outcome of /m/ under lenition).

At this stage, there were various more or less allophonic assimilation rules in place, including some that functioned across word boundaries (so-called sandhi). One was that nasal consonants merged with a following consonant to yield a single sound that maintained the nasality of the nasal and the place of articulation and voicing of the following sound. For example, in *vən dɨð ‘my day’, the /nd/ cluster would be reduced to just /n/ (nasal + dental/voiced), and in *vən ki ‘my dog’, the /nk/ cluster would be reduced to /ŋ̊/ (nasal + velar/unvoiced). This was manageable, because it happened everywhere that nasals butted up against another consonant – both within words and across word boundaries.

Later on, though, the nasal consonant at the end of *vən was lost, leaving *və (this happened before Old Welsh, but it’s still the same in Modern Welsh, and it’s what we write fy). This happened throughout the language – final nasals at the end of unstressed syllables were lost.

Something slightly unexpected happened when this occurred: the nasal assimilations described above were kept in place, even though the nasal itself wasn’t there anymore. So suddenly on the surface you had *və + dɨð and *və + ki => *və nɨð and *və ŋ̊i. The noun changes based on what comes before it, but in a way that isn’t logical and must be memorised.

So how do you write that?

Well, in Old Welsh, they clearly wondered about this too, and didn’t really come up with a good solution, though they did come up with at least half a dozen bad ones.

  • Often they would just write the underlying forms, so fy dyd and fy ci (dyd being the most common Old Welsh spelling of what is now written dydd ‘day’).

  • Other times they would indicate that something was supposed to change by reinstating the nasal at the end of the word from where it had been lost, often even writing out exactly which nasal sound was pronounced: ⟨n⟩ for dental, ⟨m⟩ for bilabial and ⟨ŋ⟩ for velar. They would then write fyn dyd, fym byt ‘my world’ (byd in Modern Welsh) and fyng ki. These are the forms you see in the dictionary.

The former approach is clear enough if you’re Welsh, ’cause you automatically know that anything coming after fy should be nasalised; but it’s frightfully rough on foreigners learning the language, who have to remember that fy causes nasalisation while dy ‘thy’ causes lenition.

The latter approach has the disadvantage that you have two consonants, in two separate words, representing a single sound – and how do you know that fym byt is /vəˈmɨd/ (one sound) while am byth ‘forever’ is /amˈbɨθ/ (two sounds)?

This is the reason why, in Modern Welsh, initial mutations are only indicated on the word that changes: you write the sound you pronounce, not the underlying sound, thus fy nydd ‘my day’, fy myd ‘my world’, fy nghi ‘my dog’ (where ⟨ngh⟩ represents /ŋ̊/). The only trouble now (though it is still a source of frustration for learners) is that you need to know the language to know that nydd is listed under d in the dictionary.

  • 2
    This is a good answer. I'll just add that in the case of the preposition yn meaning "in" (but not some other uses of yn) as well as it taking nasal mutation, the preposition itself is respelled. So yn Aberystwyth, but ym Mangor ("in Bangor") ym Mhontypridd ("in Pontypridd") and yng Nghaernarfon ("in Caernarvon")
    – Colin Fine
    Commented May 21 at 20:28
  • Thank you so much for the explanation. It clears up much of what is in the translation dictionary and more interesting to me a few word etymologies I've been wondering about. Commented May 21 at 22:24
  • @ColinFine Yes, in that one specific case, the assimilation is still written out. I don’t think there are any other words left where that’s done now, but in Old and especially Middle Welsh, it wasn’t uncommon to see assimilatory variants written out in all parts of the lexicon, like glym mawr ‘big valley’ (instead of glyn mawr). Commented May 21 at 23:56

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