1. a. Verb - the act of removing someone from your category of friends generally, not limited to removing them as your friend on any social network.
2. Noun - someone who used to be your friend, but you no longer consider them to be a friend, for any number or variety of reasons.
Sookie asked her a couple weeks later about it, "What, I thought you two were tight?" Tilly shrugged. "Well, we used to be bffs but now we're unfriends and that's just how it is."
Compulsive people prune their friend list periodically, removing people that they no longer have contact with. More often though, unfriending is only done when a particular friend's updates and self-promotions become so annoying that you can no longer stand hearing about them. Or you might unfriend someone when they piss you off, however, this is not very effective since the person who is unfriended is not notified that you unfriended them and you'd be better off to keep them as a friend and plot your revenge.
One of the many ways to bitch slap someone on 'Teh Interweb'. Often happens in a domino effect, especially when one person doesn't like you - and they're good at influencing other people. With the right amount of pressure, one 'Unfriending', will lead to several.
But if that one person (ususually known as the queen bee) happens to 'Refriend' you, you'll notice the other drones will follow suit, because they are Borg, and have been 'assimilated'.
See minion, bitch, LiveJournal, slave, mindless, sheep, poser, drone, hive, insect.
"No. Sorry. I didn't. Why do you hate them? What did they do??"
"Does it matter? WE JUST DO. Now UNFRIEND them from your Journal and get with the program!"
I find it stupid how there is no real antonym for befriend in the real dictionary, so i am creating one here.