Originally Posted by Ser Clegane
In biology, a lifeform has traditionally been considered to be a member of a population whose members can exhibit all the following phenomena at least once during their existence:
1. Growth
2. Metabolism, consuming, transforming and storing energy/mass; growing by absorbing and reorganizing mass; excreting waste
3. Motion, either moving itself, or having internal motion
4. Reproduction, the ability to create entities that are similar to, yet seperate from, itself
5. Response to stimuli - the ability to measure properties of its surrounding environment, and act upon certain conditions.