The Romans were never able to conquer Germany, but they certainly stole English from the Germans. Originally a first cousin of German, English has acquired so many words from other languages, mainly Latin, that they now outnumber the Germanic roots four to one.
The resulting language is is a strange, hybrid monster.
Since English isn’t picky about how it creates new words, we’re always adding vocabulary. When students complain about how many words Latin has, I remind them that by some counts, English has over a million words. The Oxford Latin Dictionary has only about 40,000.
Prefixes are one way we add words in English, and many of these are stuck to Latin words. Because English draws both from Latin and German there are many redundancies: in– (along with its clones ir-, im-, and il-) and un– mean the same thing. Both turn a word into its opposite: necessary, unnecessary; sincere, insincere.
What’s sort of strange is that there are tacit rules about which prefix is used. We don’t have inhappy or unpossible. Who decides these things? In– is usually preferred with Latin roots, but necessary, a Latin word, has unnecessary as its opposite.
Further confusing things is the other prefix in- that means ‘into’: influence, induction, influx.
When we see a word like inflammable, how do we know whether it means ‘not flammable’ or ‘able to burst into flames’? It means the latter, but most trucks carrying combustible material use flammable, just so there’s no confusion.
And then there’s anti-, contra– (counter-), non-, dis– and a-, all used in much the same way: matter / antimatter, clockwise / counter-clockwise, advantage / disadvantage, sense / nonsense, symmetrical / asymmetrical.
When my students complain that Latin doesn’t make sense, these are the examples I pull out and ramble about for twenty minutes or so. By then, they’re all saying, “Can we just get back to Latin?” Mission accomplished.