Some brief definitions:
Metropolis - a major city (Greek “mother city”)
Megalopolis - a region of multiple connected and interacting large cities (Greek great city)
Cosmopolis - A city with people from many different cultures (Greek world (cosmos), city)
Ecumenopolis - A planetwide city, like Coruscant in the Star Wars galaxy (Greek the inhabited civilised world, city)
Microcosm - Very small things (Greek “small world”)
Macrocosm - Very big things (Greek “great world”, the Universe, the Cosmos)
I want to define a new word:
Policosm - A world of cities (Greek city world)
The Policosm differs from A Cosmopolis (or Cosmopolitans) which describes a city (or people who inhabit cities) based on its inhabitants. The Earth, for instance, is not an Ecumenopolis, at least not yet, because it is mostly, in terms of land area, not urban. But the majority of people on Earth, and the vast majority of my readers, inhabit the Policosm, the world of cities.
It matters less on Earth which country you live in, then whether you live in cities (which are in many ways very similar), or the country. One has more in common living in metropolitan Sydney with a New Yorker than with someone who lives in the Bush of Australia. Aside from not inconsiderable language differences, you might even have more in common with someone living in Tokyo or Seoul or Shanghai or Warsaw. The distinction between cities remains, they are spatially separated (or at least various megalopolises are), and have different climates and geologies. But their city-ness abounds. Life in a neighbourhood of 15,000 people per square km is more similar in different cities than the neighbourhood of 15,000 is with the neighbourhood of 1,500 p/km^2 within the same city.
Do we need this word? I think so.
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