The word-orchards of some languages keep their rootstocks and seedstocks very much unchanged. The trees and vines might age and mutate some, but they remain largely uninvaded – there is little in the way of foreign rootstock introduced.
English is not like that.
The orchard of English is a mixture – I was going to say a wild mixture, but for much of it it’s really quite carefully cultivated, so I’ll say a somewhat crazy mixture – of mainly invasive species. We do not make do with what we have. We are quite happy taking cuttings and seedlings and such like from other languages. Most of our wordstock is not originally from English roots.
But there are still Germanic roots. The central words that are the heart of the language come from them. So do various less-used words. Words for family members, such as uncle, are grown on old Germanic roots. Words for familiar creatures – familiar to residents of Britain more than a millennium ago, and to residents of Germany and environs before that – also often spring from Germanic roots, from common bird and deer and hound to less-popular ones such as eft (a newt – which was once an ewt). And some but by no means all of our prefixes and suffixes are Germanic – non comes from Latin, but un is good Germanic.
English words also go through their mutations, cross-breeding, and such like, often with foreign stock, but also sometimes with other native stock. Somehow a word for “divide” and a word for “adhere” came to have the same form: cleave. How can you divide the two? Use the past participle – cleft only means “divided”.
Uncleft thus means “undivided”. But you’re not going to see it a whole lot. And you’re really not going to see it used much as a noun. On the other hand, there is a word we have taken from Greek that in the original means “undivided” or “indivisible”: ἀ a “not” and τομος tomos “cut, cutting, that cuts” come together to make atom, that particle originally thought indivisible.
Now imagine how it would be if English didn’t take cuttings from other languages. How it would be if it were uninvaded, undivided; if it did not cleave to roots borrowed in more recently from other languages but remained cloven from, and uncloven by, them. What sort of wine of words would we make from this terroir? (Not one that included the word terroir, to start!)
English would more closely resemble its Germanic relatives, to be sure. It would also need quite a lot of words compounded afresh from elementary rootstock to signify things for which we have borrowed words from other languages – more like making molecules from atoms than like blending wine, really.
The great science fiction author Poul Anderson once made a lovely demonstration of the sort of thing we would get. He wrote a primer (um, I should say a firstword, I guess) on atomic physics – which is to say, worldken of unclefts – in an English made entirely on Germanic wordstock, to an approximation of how English might be if it did not borrow like a magpie all the time. The result is sentences such as “The firststuffs have their being as motes called unclefts.” Which means “The elements exist as particles called atoms.”
You can read the whole text of this essay, “Uncleftish Beholding,” at www.grijalvo.com/Citas/Peculiar_English.htm. (It is followed there by two shorter texts by someone else that use almost exclusively Greek loan words in English.) And then you can decide for yourself which way you prefer your English to cleave.