Then where did the concept of "rebirth" come from? This blew, and is still kinda blowing, my mind:


  "The Buddha never, afaik, used a term that could be translated as
  "rebirth". In fact, the idea of anything being reborn goes against
  orthodox early Buddhist teachings." (from this comment by
  Yuttadhammo)


So... I have always thought of "rebirth" as being a fundamental concept of Buddhism. Sure, it's "real" meaning is debated, but the fact that there is something to it has, in my studies thus far, never been brought into question.

My real question might be something like, "What the heck?!".... But in terms of presenting something here more formal, I ask: If this is the case (and if not, perhaps you can explain why you disagree with Yuttadhammo's assertion), then where did the concept of "rebirth" come from? Why is it a topic of discussion?
Bhikkhu Bodhi writes:


  The Buddhist term for rebirth in Pali is "punabbhava" which means "again existence". Buddhism sees rebirth not as the transmigration of a conscious entity but as the repeated occurrence of the process of existence. There is a continuity, a transmission of influence, a causal connection between one life and another. But there is no soul, no permanent entity which transmigrates from one life to another.


The word "rebirth" might be inappropriate since it implies something that borns again (and that's unlikely the meaning of what the Buddha meant). I understand this is what yutthadammo was saying. But, for better or worse, it is this english word that has been used to describe the process of "continuous becoming" in buddhism in english.

"With the break up of the body, after death, he/she reappears at ...", that's what we read. As ven. Bodhi said, The difficulty with this is the doctrine of anatta: if no part of our constitution is fixed, we can't talk about something that transmigrates or is reborn.

But at the same time, we can't say the being that died and the one that reappeared are completely unrelated. What has been said is that the "relation" (or, perhaps better, continuity) is the kamma.


  "Student, beings are owners of kammas, heirs of kammas, they have kammas as their progenitor, kammas as their kin, kammas a as their homing place. It is kammas that differentiate beings according to inferiority and superiority."
  -- MN 135