One of my favorite words in the English language is "defenestration", largely because it exists.
For the uninitiated, "defenestration" is the throwing of a person or thing out of a window.
I don't know what it is, but there's something appealing about the idea that people got thrown out of windows so frequently that one day someone had to say, "You know what? My life would be so much easier if I had a word for this."
As it turns out, "fenestration" is also a word meaning "the design and disposition of windows and other exterior openings of a building" (dictionary.com), which implies that defenestration doesn't mean "the action of throwing a person out of a window" but instead "the action of removing the windows by throwing a person out of them," which is kind of funnier.
Of course, this is where I have to crush all of your dreams and bring up the facts. (All of this information is from dictionary.com because it's so gosh-darned convenient.)
Apparently, "defenestration" originated from an incident in 1618 (though the word is listed as originating in 1620) in Prague when some important Catholics were thrown out of a window (and into a moat, so hopefully not too much broke) by some Protestants, thereby marking the start of a war. (Defenestrate as a verb didn't show up until 1915.) So I was sort of right about it being invented when some dudes got chucked out of windows. I guess people didn't feel like they were intelligent-sounding enough if they said "and then they got thrown out of the window" or thought that was too much of a mouthful.
On the other hand, "fenestration" originated in 1846 (the alternate anatomical meaning of surgically forming a window in the body came later in 1870).
Both words are derived from the same Latin word, fenestra, which means window, but from what I understand, they were derived independently.
So no, defenestration was not derived from fenestration, which is a shame. On the other hand, some guys totally got thrown out of some windows and someone invented a word to commemorate the occasion, and that's still pretty cool.
(Unless you're the one getting defenestrated, of course.)