Sending an invitation very last minute with the hope invitee will already have plans. Unvites are used when you do not want someone to attend but NOT sending them an invitation would be rude.
An Unvite will say something like this:
"Sorry such short notice; I'll understand if you can't make it."
noun: An invitation to something where the inviter already knows there's no way the invited can possibly make it. That way he still gets credit for pretending to want to hang out with them.
verb: The act of inviting a person to an event, knowing full well that that can't make it, when you didn't really want them to go anyways.
noun: "Yea, I got the 'unvite' again from Shane. He knows I can't possibly go to Halloween Horror Nights this weekend, what a douche. Then he acts all upset that I can't make it. He's such an ass."
verb: "Philip has to study for a final tonight, so he can't go. Prolly I'll unvite him anyways. That way I still get credit for asking him to hang out"
When you see somebody you haven't seen in awhile, and you invite them to your abode with the expectation that they will not come over.
"Hey so did you get invited to Brianna's party tonight?"
"Yeah did you?"
"Kinda...he found out through us, so though pity she unvited him."
To un-invite somebody. After you have given an invitation you change your mind and go ahead and un-invite them. Ref: from the Seinfeld episode
I got an unvite. I've just been unvited!