The term "organism" (from the Ancient Greek ὀργανισμός, derived from órganon, meaning instrument, implement, … See more

Among the criteria that have been proposed for being an organism are:
• autonomous reproduction, growth, and metabolism
• noncompartmentability – structure cannot be divided without losing functionality. … See more

A unicellular organism is a microorganism such as a protist, bacterium, or archaean, composed of a single cell, which may contain functional structures called organelles.
A … See more

Viruses are not typically considered to be organisms, because they are incapable of autonomous reproduction, growth, metabolism, or homeostasis. Although viruses have a few enzymes and molecules like those i… See more

All organisms that exist today possess a self-replicating informational molecule (genome), and such an informational molecule is likely intrinsic to life. Thus, the earliest organisms also presumably possessed … See more

• "The Tree of Life". Tree of Life Web Project.
• "Indexing the world's known species". Species 2000. aims to enumerate all known species. See more