Lifeform

Noun: ''Something alive. An informal term for living creatures in general.''

The very term "life" is difficult to pin down. Many things have been found that lightly bridge the divide even by real life modern standards. Viruses for example. Not every biologist will agree that viruses are alive. They will still give you a cold.

Life is considered to be a complex that consumes, respirates, and reproduces. In Star Trek terms a lifeform doesn't even have to be organic by the scientific definition, that is contain carbon. Silicon based and stranger lifeforms have been described.

Consciousness is not required. Many lifeforms have little or no awareness of their environment. Most don't even have anything you can describe as a nervous system.

Consume
Life has to feed. Life has to get energy from something and to that end will take in a substances, extract energy from that substance and return the altered substance to the environment. What and how it is consumed do not matter. Something has to be consumed.

Respirate
In the process of metabolizing the complex requires other non food supplies, usually simple molecules that it will bring into the complex. Waste molecules are exhaled in turn.

Reproduce
Lastly life reproduces itself. The complex makes more like complexes. Method and means will vary, sometimes beyond casual understanding. However, for life to be considered present, this must happen.