Sometimes words in Welsh and Latin are similar because Latin and Celtic seem to have split up a (relatively) short time ago. Though it’s disputed “exactly” how long ago, if you can be exact in such things, and it is still a long time ago by most standards!
In the original post, the words “cant” for hundred and “canwr” for singer seem to be similar simply because they are both derived from the same source, rather than taken from the Latin.
You do get a “h”<>“s” thing in Latin and Welsh, and many other languages. Haul<>sol, halen<>salis, haf<>summer, Hafren<>Sabrina<>Severn, and many others. But also saith<>sept<>hept, where Welsh is more similar to Latin than Greek in that way. It seems to be a common sound change.
However, the superficial similarities to Greek did lead to some mediaeval writers using this as proof for the Welsh descending from the Trojans, an idea apparently still around when Pistol called Fluellen a “base Trojan!” In Henry V!
Though as Dee says, there are many reasons why words can be taken in from other languages- the human population is an enormous, organic thing, not responding to defined laws which can predict what words become popular, and you do simply get some words taken in, well, “because”!- I was myself always a bit thrown by the “braich” borrowing. I’ve read of some similar words in Irish possibly being around, but .i have never been able to track them down.
However, there is a simpler explanation which I’ve come to think is more likely. Perhaps the Celts didn’t have a word for arm.
For just arm, that is.
Now, I have no knowledge of Irish. But reading about a bit, it seems that the Irish word “lamh” (ie, our “llaw”) stands in for both “arm” and “hand”.
If this was the case in Roman times, you can see how it would be possible for such a word as braich to become used- it would not be replacing a native word, and could actually have been seen as a useful addition.
Just a theory which I have not seen elsewhere, My knowledge of Irish is negligible, so it could well be complete rubbish!
Ps- I don’t think the Romans actually thought of the planets themselves (or what we call planets today) as Gods. More that they were simply named after them. There was a certain “anthropomorphisation” of the Sun and into Helios, Sol, even Appollo etc. and of the moon into Luna, Diana and even Athena, but I don’t think this happened with the five visible [other!] planets, as it were. I think they were just named after them. Maybe some astrological stuff, I don’t have enough interest in that to find out! But I don’t think the planets were regarded as Gods in the same way that the Sun and the Moon were. I could well ( ie probably) be wrong.
[ edit- hmmm… There’s a tendency in Welsh in older texts for “Dwrn” to cover hand as well as fist. No idea if any of that survives. This might be a hangover from the method of making a distinction when necessary before the “braich <> llaw” thing came in. This is pure head-in-the-clouds guessing though.]
