A holarchy, in the terminology of Arthur Koestler, is a connection between holons – where a holon is both a part and a whole. The term was coined in Koestler's 1967 book The Ghost in the Machine. The term, spelled holoarchy, is also used extensively by American philosopher and writer Ken Wilber.
Holarchy is commonly referred to as a form of hierarchy however, hierarchy, by its definition, has both an absolute top and bottom. But this is not logically possible in a Holon as it is both a whole and a part. The "hierarchic relationship" between holons at different levels can just as meaningfully be related with terms like "in and out", as of "up and down" or "left and right"; perhaps more generally, one can say that holons at one level are "made up of, or make up" the holons or parts of another level. This is evident in the holarchic relationship (math <-> subatomic particles <-> atoms <-> molecules <-> macromolecules <-> organelles <-> cells <-> organs <-> bodies/individuals <-> communities <-> societies) where each holon is a "level" of organization, and all are ultimately descriptive of the same set (e.g. a particular collection of matter). Like a Fractal, the top can be a bottom, and a bottom can be a top, and the patterns evident at one level can be similar to those at another.
 Different meanings
David Spangler uses the term in a different meaning: "In a hierarchy, participants can be compared and evaluated on the basis of position, rank, relative power, seniority and the like. But in a holarchy each person’s value comes from his or her individuality and uniqueness and the capacity to engage and interact with others to make the fruits of that uniqueness available."
 Holarchy in Multiagent Systems
Multiagent systems are systems composed of autonomous software entities. They are able to simulate a system or to solve problems. Holarchy may be easily mapped to hierarchy of agents in which an agent is composed of agents and may have its own behavior as a partial consequence of these part's behaviors.
Janus Multiagent Platform is a software platform able to execute holarchy of agents.
 See also
- Holism in ecological anthropology
- Modular design
- Ontology modularization
- Process philosophy
- Sacred geometry