As used in, ‘I wrapped you in my cóta mór in the dead of night unseen’ (Skibbereen lyrics)?
Is it some kind of blanket?
over coat
Oh.
Thank you. 
The expression translates literally as “big” or “great coat”, and interestingly, in English, the term “greatcoat” is still used in military parlance for the garment.
Just to add to your store of useless information, the Irish equivalent of the national guard is known as the FCA (from the Irish-language name which means “local defence force”). Cynics claim that the initials stand for “free clothing association”, because in rural circles in the bad old days of serious hardship the boots and greatcoat were greatly prized - the boots for working wear and the greatcoat as an extra-warm bedcover.
Roger,
Just so you know, it wasn’t only the bogtrotters that valued the Free Clothes Association. There was a family of sixteen that lived two doors away from me in Crumlin and most of them were kitted out in hobnail boots and green jumpers and pants, courtesy of Collins’ Barracks, because one of the boys signed up to do his bit for Dev. I still remember the time the swine threw a few .303 rounds into our bonfire one night.
Ah, the innocence of youth.
That wasn’t on Raphoe Road, 1950s, by any chance, was it?