[mythically from a traditional Bohemian assassination method, via SF fandom]
1. Proper karmic retribution for an incorrigible punster.
Oh, ghod, that was awful!
Quick!
Defenestrate him!
2. The act of completely removing Micro$oft Windows from a PC in favor of a better OS (typically Linux).
3. The act of discarding something under the assumption that it will
improve matters. I don't have any disk space left.
Well, why don't you defenestrate that 100 megs worth of old core
dumps?
4. Under a GUI, the act of dragging something out of a window (onto
the screen). Next, defenestrate the MugWump icon.
5. [obs.] The act of exiting a window system in order to get better response time from a full-screen program. This comes from the dictionary meaning of defenestrate, which is to throw something out a window.