It really hit me the other day just how cynical and filthy-minded I am when I saw the word conurbation and immediately thought it was a portmanteau for congressional masturbation.
I am so disappointed in myself.
The con part of conurbation is the same prefix that's on Congress (as well as contemplate conflict and condemnation), meaning "together" or "with." The urb part is from the Latin word meaning "city."
A conurbation, then, is cities coming together. Its the commingling of large cities into a single megalopolis, what more often in the United States is called a greater metropolitan area.
Examples of conurbations include Dallas–Fort Worth, Minneapolis–St. Paul, and, I guess, all of the planet Coruscant, another victim of excessive conurbation.
The word conurbation was coined in 1915 by Patrick Geddes in his book Cities in Evolution. Those who have read David Mitchell's Cloud Atlas or saw the movie version might recall that the overpopulated city of the future was called a conurb. Even in the future, people just can't get enough of their abbrevs.