You said it. Any basic character or attribute that defines your life, although I remember one old thread in evolution claiming that scientists can not define what life truly is. Try watching The Core and the Dr. Zimsky there said that science is all about guess… so there comes the theories work.

There are some common characteristics of current Life: cellularity, energy transformation, reproduction, evolution of populations, response to environment, a couple of others. Some would be thought to apply to anything that could be called "life."

as there is nothing like "life" or "vital power" by itself, as people used to think, no, it probably isn’t

I don’t think there is a universal, compact and accepted-by-all definition of life. It is just a combination of phenomena that we typically see in things we say are ‘living’.

There’s difference between existing and living..everyone has different definition of life(philosophically speaking)..when one exists,he’s only in the waitingroom..waiting for life..basic (biological) needs are fulfilled..but life is more..for me it’s investigation and creativity

Think of it this way; imagine the very first self replicating organism that is the ancestor to every organism we class as alive. Life is all of the individuals that have occurred in the lineage originating from that first individual. Essentially the tree of life is the very definition of life because its generally accepted that all living things share common ancestry.