Further on djwebb’s post (móirín), I’m still curious of its origin. Any comments would be appreciated. https://en.m.wikipedia.org/wiki/Our_Lad ... of_the_Sea

So, as you're probably well aware, Máirín is pet form of Máire formed by adding the diminutive suffix -ín. This means that really the etymology we need to examine is that of Máire.

The most likely etymology is a direct borrowing from Latin Maria, itself from Greek Μαρια (Maria). This is the etymology suggested by eDIL, which goes on to state that the form Maire was used in the oldest religious texts, with it later turning into Muire.

I don't see how the Latin Stella Maris would have turned into Old Irish Maire based on the sound changes that occurred between Archaic and Modern Irish. It's easy to see, however, how the Latin form Maria would have been adopted into Irish directly as Maire, because the internal consonant r would have been difficult to pronounce between one broad and one slender consonant. Assumedly Maire originally had a diphthong, -ai-, which later became a long á.

Conversely, it's actually possible that a translation from the Latin, Stella Maris, into late Old Irish could have produced the form, Muire, as opposed to Máire. This is because muir could be treated as feminine noun in late Old Irish, and the genitive form, muire, is attested from this period. This would have resulted in a translation something like rind muire for "Star of the Sea". Two things are difficult to explain about this, though. Firstly, why did it turn into a proper noun, having originally been more of a description, like the English "Star of the Sea". Secondly, if one of the words were to be dropped, why would it be the first one which is in the nominative form? Why, instead, was the genitive form of the second noun retained, even without the first noun to provide grammatical context? While this explanation may be possible, I should say, it all seems a little too much of a stretch to me, in particular because this only works if the translation from the Latin Stella Maris occurred in the Late Old Irish period, when the genitive form of muir could be muire. Any earlier or later and the more likely forms would have been moro or mara. That just seems like too small a window of opportunity to both translate the term into Irish from Latin, for it to catch on, and for the genitive form to become fossilised as muire in this context even after that form ceased to be grammatical.

In the Wikipedia article, it explains that "the star of the sea" references the Virgin Mary, whether or not it's perfectly etymological or not. These things have happened and there may be other examples which escape me at the moment . . .

I'm not sure I understand. "Star of the Sea" is a reference to Our Lady, but how this is linked to the Irish Máirín is unclear to me etymologically. Despite such an etymology being mentioned by many resources, it doesn't seem to be borne out by early attestation according to eDIL.

The Wikipedia article has nothing to do with Ireland. But muir=sea and Muire=the Virgin Mary, so there is a possible link. It's difficult to forge the link straight from Máire. And then if you look at the genitive mara, it gets a bit closer to Máire, but not quite.