A Chemical System Capable of Evolution
This definition encompases all life we know yet gives wide lattitude for alien life forms. It's a simple way to distinguish truly alien life from simply alien chemistry without limiting the definition to something closely resembling our form of life. And yes that makes viruses alive. Always thought it was stupid to claim they weren't. It would seem very odd to me to claim viruses aren't alive yet to claim "ancestors" of current life that were based on RNA or some other coding system were. The same is true for alien life based on some other genetic code.
Regards,
Mark