Incorrect.

Im - defined as not

Mortus - defined as death

Basically, immortal means no death. Therefore, if something is immortal, it cannot die. Besides, the jellyfish dying would seem more of an asexual reproduction, not constant regeneration.

I've seen people confusing the two things in the thread for quite some time now. Immortality is not the same as invulnerable. There are a lot of bacteria which are immortal too, or at least immortal given their extremely long life span, as they live on creating the same copy of itself (no change to its DNA). 
But if someone disrupts it or enviromental factors kick in and denaturate the bacterial cell, it dies, even though it's immortal. That's because nothing is invulnerable. As we're (every living thing) made of proteins and a bucketload of other organic matter, there's not a single being that's invulnerable.

Relativity says hat time won't exist without the universe, and it didn't exist before the universe.

Wrap your head around that shit.

@dtewi:

There are two accepted meanings of "immortal" - literally being unable to die is just one of them, and it's much more narrow and imaginary.

But technically speaking, that is the more correct definition.

Immortality is not imaginary though (well, as of now it seems to be). It could be possible in the future.

Very very far into the future.

*sigh*

No, it's not. The etymology of the word was used to describe gods and spirits who never died. Or concepts that aren't capable of death and would never be forgotten. Or ties that would never be broken. Or rocks.

The definition of words can't be traced that easily through the roots, because there are implications in every definition of every word - immortality is that which lacks mortality, and mortality doesn't just mean the quality of being able to die, it also means being limited, and it also means being subject to age.

You can't have a "more correct" definition!

Go to your room and don't come out until you've thought about the crimes you've committed against your language!

So what you would prefer me to say?

That the etymology of the word suggests a more clear idea that its connotation means to not be able to die?

That is long-winded.

Etymology is more than just the roots of a word - it has to do with past usages, too. And immortal tends to not refer to things that live but cannot be killed.

You could say "You know, a literal interpretation of the roots of the word suggests something kind of like the Highlander minus the decapitation weakness", but even tat isn't quite right in that it's only one definition of "mortality".

You could say "You know I always thought of immortality as being literally unable to die"

Or you could just say

"Holy shit that jellyfish could live for a billion billion years in ideal conditions"

aww man does this mean theres no heaven or hell geez....

Can it live in a bathtub? I wanna buy one and just watch it live forever.