"Duine cunnartach."

Translation: A dangerous person.

[Mirokha]

I wonder why it is not spelled as cunnairtach - the way it is pronounced.
The same with ceart > ceairt...

[silmeth]

Why would it be spelt that way? It wouldn’t be etymological and it would break the leathan ri leathan, caol ri caol rule (although with consonant clusters it sometimes does happen when only one of the consonants is slender).

But there is no difference between unlenited slender and broad /R/, they both sound the same (if they didn’t, those words would have the broad /R/ anyway) – and since r here appears in a consonant cluster (and not between vowels) it’s unlenited.

If you are confused by the /ʃ/ sound between them (rt and rd sounding as if /Rʃd/) – that’s a common phonetic phenomenon in many (but not all) Gaelic dialects. That doesn’t mean that /R/ is slender, it’s just /ʃ/ being inserted between two consonants in a cluster.

You can read about it on the Akerbeltz wiki and here.

[Mirokha]

You are right, it's dialects...

I would not say I am confused by /Rʃd/ /Rʃt/- we have the same thing quite developed in Slavic languages. Only historically [ʃ] appeared at slender [r'], never at broad [R]:
[r'] кремний, пришёл, репа, ряд
[rsh] [rzh] křemík, přišel, řepa, řada
[sh] [zh] krzem, przyszedł, rzepa, rząd

[silmeth]

Hehe, I am a native Polish speaker. :)

I don’t think it’s the same in (West) Slavic languages – in Czech ř is [r̝], a raised [r] which you could also describe as a sound like [ʒ] but with additional trill. In Polish it just fell together with /ż/ into a single [ʒ ~ ʐ] sound, but we still differentiate it with rż /rʒ/ and rsz /rʃ/ as in rżeć /rʒetɕ/ (to neigh, to make a horse’s sound) and wiersz /vʲjerʃ/ (verse, poem) which shows that this is different that simply adding /ʃ ~ ʒ/ to /r/ (they did not became the same, rz and rż are still different in modern Polish).

Gaelic just inserts /ʃ/ between /r/ and /d/ and doesn’t really care whether it’s palatalized or not.

But anyway it’s true that r-like and z-like (or s-like) sounds tend to come together and change into one another… compare Latin corpus, corporis (from older corposis) or English was, were from OEn. wǣron from PGerm. *wēzum/d/n.

[Mirokha]

Yes, they are different from the way I described them [zh] [rzh], but that was because I didn't know who I was talking to. :)