An oikos (ancient Greek: οἶκος, plural: οἶκοι; English prefix: eco- for ecology and economics) is the ancient Greek equivalent of a household, house, or family. An oikos was the basic unit of society in most Greek city-states, and included the head of the oikos (usually the oldest male), his extended family (wife and children), and slaves living together in one domestic setting. Large oikoi also had farms that were usually tended by the slaves, which were also the basic agricultural unit of the ancient economy. The Greek oikos differed significantly from the Roman domus in architectural layout...

Polis (/ˈpɒlɨs/; Greek: πόλις [pólis]), plural poleis (/ˈpɒleɪz/, πόλεις [póleːs]) literally means city in Greek. It can also mean citizenship and body of citizens. In modern historiography, polis is normally used to indicate the ancient Greek city-states, like Classical Athens and its contemporaries, and thus is often translated as "city-state". The Ancient Greek city-state developed during the Archaic period as the ancestor of city, state, and citizenship and persisted (though with decreasing influence) well into Roman times, when the equivalent Latin word was civitas, also meaning "citizenhood...

The cosmos is a complex and orderly system, such as our Universe; the opposite of Chaos. It is the Universe regarded as an ordered system. The philosopher Pythagoras is regarded as the first person to apply the term cosmos (Greek κόσμος) to the order of the Universe. == Cosmology == Cosmology is the study of the cosmos in several of the above meanings, depending on context. All cosmologies have in common an attempt to understand the implicit order within the whole of being. In this way, most religions and philosophical systems have a cosmology. In physical cosmology, the term cosmos is often used...