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.
The term is Greek (Greek: Î¼Î·ÏÏÏÏÎ¿Î»Î·) and means the mother city of a colony (in the ancient sense), that is, the city which sent out settlers. This was later generalized to a city regarded as a center of a specified activity, or any large, important city in a nation. A big city belonging to a larger urban agglomeration, but which is not the core of that agglomeration, is not generally considered a metropolis but a part of it. The plural of the word is most commonly metropolises, although the correct plural is metropoles, Latin from the Greek Metropoleis (Greek: ÎÎ·ÏÏoÏÏÎ»ÎµÎ¹Ï).