Semantics
The word organism may broadly be defined as an assembly of molecules functioning as a more or less stable whole that exhibits the properties of life. However, many sources propose definitions that exclude viruses and theoretically possible man-made non-organic life forms. Viruses are dependent on the biochemical machinery of a host cell for reproduction.
Chambers Online Reference provides a broad definition: "any living structure, such as a plant, animal, fungus or bacterium, capable of growth and reproduction".
In multicellular terms, "organism" usually describes the whole hierarchical assemblage of systems (for example circulatory, digestive, or reproductive) themselves collections of organs; these are, in turn, collections of tissues, which are themselves made of cells. In some plants and the nematode Caenorhabditis elegans, individual cells are totipotent.
A superorganism is an organism consisting of many individuals working together as a single functional or social unit.
Read more about this topic: Organism