What is City?

Legal Definition
A city is a large and permanent human settlement. Although there is no agreement on how a city is distinguished from a town in general English language meanings, many cities have a particular administrative, legal, or historical status based on local law.

Cities generally have complex systems for sanitation, utilities, land usage, housing, and transportation. The concentration of development greatly facilitates interaction between people and businesses, sometimes benefiting both parties in the process, but it also presents challenges to managing urban growth.

A big city or metropolis usually has associated suburbs and exurbs. Such cities are usually associated with metropolitan areas and urban areas, creating numerous business commuters traveling to urban centers for employment. Once a city expands far enough to reach another city, this region can be deemed a conurbation or megalopolis. Damascus is arguably the oldest city in the world. In terms of population, the largest city proper is Shanghai, while the fastest-growing is Dubai.
-- Wikipedia
Legal Definition
Government. A town incorporated by that name. Originally, this word did not signify a town, but a portion of mankind who lived under the same government: what the Romans called civitas, and, the Greeks polis; whence the word politeia, civitas seu reipublicae status et administratio. Toull. Dr. Civ. Fr. 1. 1, t. 1, n. 202; Henrion de Pansey, Pouvoir Municipal, pp. 36, 37.
-- Bouviers Law Dictionary
Legal Definition
In England. An incorporated town or borough which is or has been the see of a bishop. Co.. Litt. 108; 1 Bl. Comm. 114; Cowell. State v. Green, 126 N. C. 1032, 35 S. E. 462. A large town incorporated with certain privileges. The inhabitants of a city. The citizens. Worcester. In America. A city is a municipal corporation of a larger class, the distinctive feature of whose organization is its government by a chief executive (usually called "mayor") and a legislative body, composed of representatives of the citizens, (usually called a "council" or "board of aldermen,") and other officers having special functions. Wight Co. v. Wolff, 112 Ga. 169, 37 S. E. 395.
-- Black's Law Dictionary