Pitch is the distance from the crest of one thread to the next. Because the vast majority of screw threadforms are single-start threadforms, their lead and pitch are the same. Single-start means that there is only one ridge wrapped around the cylinder of the screw's body.
Definition of metropolis. 1  1 : the chief or capital city of a country, state, or region. 2  2 : the city or state of origin of a colony (as of ancient Greece) 3  3a : a city regarded as a center of a specified activity an industrial metropolis a cattle metropolisb : a large important city one of Europe's great metropolises.
Which one you regard as the holder of the title, all depends on what you mean by city. Most experts will tell you that Tokyo is the world's largest metropolis, with a population of about 36 million people. But the core of the city has only eight million people living in it.