An event invitation sent to someone solely for the reason that one feels obligated to do so.
For example, there are three roommates and you know two of them well. You may not know the third person as well as the other two--or you just don't like them--yet you feel obligated to invite that person too so things won't get awkward.
An insincere invitation, made by someone who does not actually intend to follow through with a genuine invitation.
Person A: "Hey! Let's get together sometime and go bowling!"
Person B, sensing an invitease: "Yea...that would be really swell...what's a good day for you?"
Person A (pretending not to hear): "Cool! See ya!"