immortal

[Maximara]

Face it the reality is immortal does not mean unkillable.

Umm yes it does, immortal literally means unkillable. All the examples you cite may have been called "immortal" in their source material, but are only virtually so as in certain circumstances they CAN be killed. It's like many people refer to Superman as invulnerable (including Superman himself) but he isn't, he's VIRTUALLY invulnerable because he CAN be harmed, it just takes a lot.

im·mor·tal   Audio pronunciation of "immortal" ( P )  Pronunciation Key  (-môrtl)
adj.

   1. Not subject to death: immortal deities; the immortal soul.

http://dictionary.reference.com/search?q=immortal

I can cite too: Thesaurus definition:

"2. any supernatural being worshipped as controlling some part of the world or some aspect of life or who is the personification of a force"

Note that this definiton says nothing about dieing. The defintion you gave is just like the one creationists used to cite for science back in the 1980's which excluded all the social sciences and just as flawed.