One definition I've ever heard for life is that it's a process which increases the entropy around itself in order to decrease the entropy within itself. It disorders the world around it to order itself.
Nearly all life gets consumed by some other form of life eventually. Often it's the bacteria and fungi and insects doing the consuming of what we might consider more sophisticated organisms. The negative entropy - all the useful molecules concentrated and precisely ordered - can be seen as the thing being consumed. Same goes for chemical or energy gradients like around deep water thermal vents or photosynthesis.
