Most working biologists quietly default to something like the NASA/chemistry definition during the day — and then lie awake at night quietly wondering whether their own aliveness is actually explained by that definition. The disturbing short answer that keeps resurfacing across disciplines is: To be alive (in the richest sense most of us mean when we ask the question) is to be a locus of mattering + caring + perspectival experiencing that is simultaneously fragile, finite, thermodynamically costly, and yet stubbornly self-asserting. In other words: something is alive, in the full human-intuitive sense, when destroying it feels like it would destroy a point of view on the universe — not just an interesting pattern. So perhaps the most honest currently-available one-sentence answer is: Alive means being an ephemeral, energy-consuming, self-referential perspective that insists — against the second law — on continuing to have a perspective. And the really unsettling follow-up question then becomes: … why do so few physical patterns get to have that privilege? What do you feel is still missing when people try to define it for you?