A zoning is the arrangement or partitioning of land areas for various types of usage in cities, boroughs or townships.

see also:
"zoning" is in the NAICS Code "541310"
  Architectural Services
  ... knowledge of design, construction procedures, zoning regulations, building codes, and building materi ...

Other definition:
A Zoning is to designate, by ordinances, areas of land reserved and regulated for specific uses, such as residential, industrial, or open space

see also:
"Zoning" is in the NAICS Code "925120"
  Administration of Urban Planning and Community and Rural Development
  ... development of urban and rural areas. Included in this industry are government Zoning boards and commi ...