I'm referring to monitors as described here:
http://en.wikipedia.org/wiki/Monitor_(synchronization)
None of the definitions here seem apropos:
http://www.thefreedictionary.com/monitor
So why are they called that?
== Update ==
Thank you for the answers, everyone!
I guess I was confused because I don't think of monitors usually as acting on themselves, which is what seems to be happening here. For example, you use a baby monitor to monitor a baby. I just don't think it would make much sense for a baby to monitor itself, but I could be wrong.