This sentence appears in the Mynediad Dwys course I am studying:
‘Dyn ni wedi bod yn gweithio dramor’.
I know that nouns and adjectives mutate after ‘yn’, but surely ‘tramor’ here is an adverb so why the mutation? Or is ‘tramor’ here treated as a noun? (We have been…overseas)
Treated as an adjective I meant to say.
I don’t know if it’s an adverb of place. In the challenges, It is mutated to dramor after the verb(s) for “travel”.
Hi Debra,
I think @garethrking is the top man to explain exactly how this works (and to correct me if what I say below is wrong!), but I’ll have a go at explaining.
Just as adjectives mutate after yn, so do adverbs (e.g. symud yn gyflym), it’s just that there are some adverbs that don’t need an yn yet they still mutate. Tramor, as you’ve noticed is one, as is cartref (e.g. heddiw dwi’n aros gartref).
I hope that helps, and maybe Gareth can elucidate further.
Yes, as usual Siaron has done the spadework here. I’ll come from a different angle to say the same thing:
There are two types of adverb:
adverbs of manner, describing how an action is performed (like -ly in English), and these are formed from adjectives by prefixing yn + SM: cyflym quick > yn gyflym quickly. There are squillions of these of course, because there are squillions of adjectives.
adverbs of time and place, telling you when or where an action takes place. This is a much more limited class, and they don’t have anything to do with adjectives. They (mostly) don’t take yn, but they DO take SM. So for example, years is blynyddoedd, which is just a noun. But if we say years ago, that is telling us when something happened, so it’s an adverb of time - and so we say flynyddoedd yn ôl. And it’s the whole phrase that takes the mutation at the front. So if we expand that one and say two years ago, then it’s ddwy flynedd yn ôl. with the SM on the dwy because that’s where the adverb starts (and the SM on blynedd is simply because of the dwy, by the way). Similarly, for example, canol mis Medi is the middle of September, but if you want to say that something happened in the middle of September, the best way in Welsh is to say ganol mis Medi - perfect! Time when, see? Ddechrau’r wythnos - at the beginning of the week, ddiwedd y ganrif - at the end of the century.
And then for place, examples like Siaron’s cartre home > gartre at home. There aren’t nearly so many of these.
That was super helpful - diolch yn fawr iawn! 
Gosh Gareth, I hate grammar but you make it almost fun.
It’s what I do, Tricia…
Many thanks for the replies which have clarified all. It’s a few years since I got my Welsh ‘O’ level…
Pedant’s enquiry here, but … is there a historical explanation for the SM on adverbs of time/place? Do philologists posit a lost particle or preposition which created the appropriate phonological environment? (eg it ended in a vowel). Or something else? Partly just curious, but also I find that knowing the origins of fossilised rules like this helps me secure them in memory!
A question for you here @garethrking 
Well that is a very interesting question, that has caused many philologists to fall out with each other over the decades.
Some say a lost preposition accounts for things like ddydd Mercher on Wednesday, assuming that it was originally ar ddydd Mercher. But this does not account for ganol mis Mai in the middle of May, which would have been yng nghanol mis Mai. But then perhaps it is ganol simply by analogy with ddydd - analogy is always a very powerful force in language change. Mind you, a further difficulty here is that ar ddydd Mercher generally means something different from ddydd Mercher, the former being routine for on WednesdayS.
This could be a grammatical mutation, of course - the SM has this on its charge sheet going way back. In other words, just as SM after the subject of the sentence is a useful way of separating subject from object in what is a Verb-Subject-Object language, so perhaps there is another neat little rule that simply says ‘use SM at the front to show it’s an adverb’. This would also neatly account for the same in adverbs of place - we always say fan hyn and not ‘man hyn’ for here, don’t we? Ditto examples like gartre (at) home - we never say ‘cartre’ for this adverbial use.
It is all very thrilling and bewildering in about equal proportions, I would say.
I have a suspicion that @aran might disagree and agree with that statement, in about equal proportions…
Thank you for this! I’m only a rank beginner at Welsh, but definitely in the thrilling-if-bewildering camp. I find it interesting that if there was a preposition, it had already been lost without a trace back in the mists of time. The idea that the mutation was originally phonological but got extended by analogy to any word that functioned as an adverb of time-when or place-where (ie became a marker of grammatical function) seems wholly plausible — and fun. Possibly ‘ar ddydd Mercher’ was able to re-emerge with its new meaning at a later date because the old phrase was no longer in use? Language users are restless innovators…
While I’m at it, can I thank you from the bottom of my heart for Modern Welsh, which came into my hands a couple of years ago and essentially made it possible to get some kind of purchase on the language, after years of baffling encounters with antique and obscurantist grammars (naming no names!..). For those of us who like a bit of book-learning to undergird language-acquisition style courses like SSiW, it’s completely transformative. As indeed is this forum and all the amazing answers that can be found here — it’s like having the world’s cleverest, most patient tutor at one’s disposal! Diolch yn fawr, pawb.
Now, if I can just get my tongue around all the fascinating quirks of the language…
Thank you for your kind words on the Modern Welsh, Sir (or is it Lady?) Midwinter - and I do agree with you about this forum…the best of its kind!