[QuercusMax]

Not at all. It's just the Latin prefix "de" (out of) plus "fenester" meaning window. Not an English word except by borrowing.

[cryptonector]

The joke was that [to my then knowledge] it's not used in Romance languages, but it is used in English.

[QuercusMax]

I believe the term originates with this historical event:

https://en.wikipedia.org/wiki/Defenestrations_of_Prague

And if you believe Wiki, it was used originally in Middle French.