I think Schrödinger in his book of the same name as the title of the article gave by far the clearest definition of life. Life is a local state of negative entropy. Which is to say that life orders matter and exports heat. There are other definitions mentioned here that are kind of equivalent, i.e life stores information, life as an out-of-equilibium state etc, but just expressing it in terms of entropy I think draws a clear line between living and non-living matter.

I think the consequence of this is that quite a few systems can be considered alive that traditionally wouldn't, like crystals or DNA itself but I don't think that's that big of a deal.