Singular usage words in literature like this have no "meaning" that anyone (even the author) can write down. A famous example is
from Shakespeare. Nobody has the slightest clue what this means, but it's very obvious what it means. Remember too that we live in a great poetic era,
from Misters Lennon & McCartney respectively. It's completely obvious what is "meant" - you are instantly and with total crystal clarity given something very specific - but you can't "look up the meaning".
Literary, suggestive, highly intense language like this delivers you a kick in the gut, and a very clear kick in the gut. But like when you look at a Caravaggio and get a Caravaggio kick in the gut, you can't write down the "meaning" or "reason" ("because of the blue color here" or the like).
Nominally "unhooped" means "a barrel with the hoops taken off", a word a cooper might use.
The only sense in which you can "state the meaning" is that a group of folks could discuss the, for want of a better word, impression, sense, emotion that is conveyed to each of them.
For me it makes me think of something not yet constructed, not yet figured-out (but then, my grandfather was in the cooperage business), so for example nowadays the oceans, even the moon, is certainly "hooped" by mankind and our technology; for others it might convey or "mean" something smashed apart, 100s of gallons of liquid flying around willy-nilly.
(I guess this issue is constant for translators. One could translate that as a range of things .. unknown, chaotic, not yet conquered, on the edge of falling apart at any moment .. etc .. all different.)