there is a state where someone is technically alive, but our current medical knowledge and technology is not able to keep this person alive and bring them back

there is a state where someone is technically alive, but our current medical knowledge and technology is not able to keep this person alive and bring them back from that state. so while they are not yet dead, there is no more hope. what happens is that as our knowledge and tech improves, our ability to "revive" someone gets better, so the state where someone is really dead gets pushed out more and more.