Every bookkeeper needs a bookcase, right?
If you’re keeping a book that was kept by a saint, then surely you’ll want a case for that, at least. Given the pure rareness and preciousness of the work – a holy relic, sure as the hair on the saint’s head (after all, books fill the space under the hair) – if you wish to argue for armored and bejewelled protection, you have a case.
Especially if you want to carry that book into battle (perhaps on a chain around your neck) as a talisman for troops. A mighty fortress is our God, but saints can make do with a parallelepiped of armor. Anyway, if a commitment to battle is binding, why not commit to a battle with a binding? You want to provide your warriors some hard cover – there’s no respect for a paperback rider.
So what is this book-shaped armour – which can also carry other relics of the saint, such as the aforementioned hair or some bones or skin? It’s called a cumdach. That’s with the ch pronounced hard (as in ach and loch), and the m not pronounced at all – apparently that little book of a letter has been bundled away somewhere.
Actually, it hasn’t. The letter that’s been absconded with is h. The Irish word that we stole away is cumhdach; the h was for a long historical period written as a superscript dot over the m (so much easier to purloin like a loose jewel). That mh can, depending on the word and the dialect of Irish, be said like “v” or “w” or not much of anything, but generally nasalized one way or the other. So the first syllable of this word would sound, in casual speech, not much different from the first syllable of coondog. If you just say it /ˈkuːdəx/ as the Oxford English Dictionary suggests, you’ll be the one stealing away a phoneme.
Cumdachs aren’t available in quantity. The vogue for them is almost a millennium in the past (especially the carrying into battle part); some of them have had their contents stolen, and others have themselves been stolen – ornamented as they typically are with precious stones. But, given that, I see no reason not to bring the word to the present for an expanded sense. If you happen to own a book that’s been hollowed out for holding precious relics of your own life (jewelry or documents, say), or if you happen to have a nice-looking box in which to carry a book of value, why not call it a cumdach? I have two nice boxes that are fashioned to look just like books. They hold my ties. They may not be saintly, but they are formal, and anyway, blest be the ties that are in a binding, right?