Someone who makes a plan, includes everyone and their mama and then cancels it at the very last minute.
Surya: "Hey Ameet, are you going to the jazz concert that Aparna is planning to get everyone to go to?"
Ameet: "Yes but you know everyone will make it except her".
Surya: "What do you mean?"
Ameet: "Well you know Aparna, she's the biggest cancellator"
Surya: "Damn! you're right..."