Hmm, a lot of Czech words aren't actually Czech, then. I think that makes even less sense. The fact is the Czech language loans heavily from many different languages (Latin being one of the top donors) - but that doesn't mean we speak a mix of languages in one sentence.

The prefix de- is not used only in loanwords, you can construct new words with it just fine. It doesn't sound right in your example but that doesn't mean it's nonsense.

"defenestrace" is a Czech word, "defenestration" is an English word, but they can both trace their origin to the latin "defenestratio".

> The prefix de- is not used only in loanwords, you can construct new words with it just fine.

Listing some examples would strengthen your argument immensely.

> It doesn't sound right in your example but that doesn't mean it's nonsense.

To my native ear, it sounds nonsensical. I wouldn't be able to guess what it is supposed to mean.

Defenestratio is not a Latin word, you wouldn't describe the act like that as a Latin speaker. You'd say something involving the words "de fenestra", but definitely not as one word.

It was the Czech person who first combined the Czech/Latin prefix, the Latin stem and the Czech/Slavic suffix in a decidedly Czech sentence.

> Listing some examples would strengthen your argument immensely.

You said one yourself. Nobody would say it because there's already a better way to say that, but everybody would understand the meaning and the grammar is fine.

"dechlupeni" is not a Czech word.

> but everybody would understand the meaning and the grammar is fine.

No, I certainly wouldn't. It's nonsense.

Can you name a word formed like that which is present in some dictionary?

Even if you're right about that, it still doesn't make the word Latin. Latin speakers wouldn't say it as one word, and there would also be a verb in a Latin sentence - "de fenestra" by itself is nonsense.

(I had the displeasure of studying Latin in school)

> Latin speakers wouldn't say it as one word

Note that all Latin speakers in that time period spoke Latin as their second (third...) language, and it was pretty common to see influence of other (mother) languages onto the used Latin. It wouldn't be surprising if e.g. a German native speaker (where such word concoctions are common place) coined such a Latin word.

It would also be unsurprising to see a native speaker of classical Latin coin such a Latin word. defenestro and defenestratio are perfectly compatible with the normal methods of word formation in classical Latin, which very rarely forms compound nouns, but which forms compounds of verbs with prepositional prefixes all the time. (Just in that last sentence, you can see the ghostly remains of perfectus [thoroughly-done], compono [with-put], praepositio [before-putting], and praefixus [before-fastened], all impeccably classical. You can also see compatior [with-endure], which does not seem to have existed in classical Latin, but is obviously derived in exactly the same way as the others.)

Here ( https://www.perseus.tufts.edu/hopper/morph?l=defatigatio&la=... ) is a dictionary entry citing defatigatio to a speech given by Cicero.