A long time ago, there were no dictionaries, no modern language associations, no Oxford standards. Language is a fundamentally organic system that has been evolving for thousands of years, as complex and intricate as something like the economy, and for most of its existence its rules have not been explicit.
The search for extra-terrestrial life tends to focus on the requirements for life on Earth: carbon, oxygen, liquid water, and so forth. There are arguments that support the idea that any life would have similar needs. Yet there are also arguments that life could be so alien that we might not even recognize it as life. Indeed, the biological definition of life can be interpreted to include things like stars, which are generally not considered "alive."