So...guns don't kill people...

[old.Tohtori]

but your looking for that next step, that final switch, the point of no return etc

Ever seen disneys hercules? your looking for the point at which the 3 witches cut the string-of-life (the blind ones who share an eyeball- actual greek mythology but not sure if the string bit was "accurate") and what exactly is happening at that exact moment?

If you want to take it, as one must to explain it, in mythical/religion terms. Yes. That final point of "nothing will bring you back save a -higher hand-", which is right out here.

If you're looking for a 'technical definition' as to what dead would be, it's Asystole. I.e no cardiac activity, so no contractions = no blood delivery to tissues/cells.

So when someone has a heart attack and they bring out the defibrillator they are technically dead for however long they're in Asystole for.

Same applies for the brain, once electrical activity ceases, processes will start going wrong/stopping and everything starts shutting down, as per vegetative state.

I'm' actually looking for something that isn't really there. Being dead, no new thing, can bring back. But is being REALLY dead, just the time when people give up on you?(morbid i know)