General English


  • In Kepler’s Laws, which govern the orbits of planets, a sector is the area swept out by the radius vector of a planet – the line joining it to the Sun – in a given period of time. It does not change in size since the planet moves faster the nearer it comes to the Sun, so that the effect of the eccentricity of the planet’s orbit is self-cancelling.


  • noun part of the flight between an aircraft moving under its own power until it next stops after landing in its allocated parking position
  • noun the portion of a circle inside two radii and the included arc
  • noun a segment of airspace with its own team of air traffic controllers


  • noun a section of a stock market, listing shares in one type of industry such as the banking sector


  • noun the smallest area on a magnetic disk which can be addressed by a computer; the disk is divided into concentric tracks, and each track is divided into sectors which, typically, can store 512 bytes of data
  • verb to divide a disk into a series of sectors


  • noun a part of the economy or the business organisation of a country. A country’s economy is divided into the public sector (i.e. the government and local authorities), the foreign sector (i.e. companies or governments based outside the country) and the private sector, which itself is made up of the corporate sector (firms which trade), the personal sector (individuals and their income and expenditure) and the financial sector (banks and other institutions dealing in money).


  • The smallest addressable portion of a storage unit such as a hard disk, optical disc, or tape. Each track consists of a given number of sectors.
  • A specific sector (1) within a storage unit.
  • A part or division of something.

Information & Library Science

  • noun a division of a group or area which is also part of a larger one


  • noun a subdivision of an area of ground