sector

[sek-ter]

noun

1. Geometry.,  a plane figure bounded by two radii and the included arc of a circle.

2. a distinct part, especially of society or of a nation's economy.

   the housing sector; the educational sector.

3. a section or zone, as of a city.

4. Military.,  a designated defense area, usually in a combat zone, within which a particular military unit operates and for which it is responsible.

5. a mathematical instrument consisting of two flat rulers hinged together at one end and bearing various scales.

6. Machinery.,  a device used in connection with an index plate, consisting of two arms rotating about the center of the plate and set to indicate the angle through which the work is indexed.

7. Astronomy.,  an instrument shaped like a sector of a circle, having a variable central angle and sights along the two straight sides, for measuring the angular distance between two celestial bodies.

8. Computers.,  a portion of a larger block of storage, as 1/128 of a track or disk.

verb (used with object)

1. to divide into sectors.

sector

/ ˈsɛktə /

noun

1. a part or subdivision, esp of a society or an economy

   the private sector

2. geometry either portion of a circle included between two radii and an arc. Area: 1/ 2 r ²θ, where r is the radius and θ is the central angle subtended by the arc (in radians)

3. a measuring instrument consisting of two graduated arms hinged at one end

4. a part or subdivision of an area of military operations

5. computing the smallest addressable portion of the track on a magnetic tape, disk, or drum store

sector

1. The part of a circle bounded by two radii and the arc between them.

Other Word Forms

• sectoral adjective
• subsector noun

Word History and Origins

Origin of sector¹

First recorded in 1560–70; from Late Latin, from Latin: “cutter,” from sec(āre) “to cut, divide” + -tor -tor

Word History and Origins

Origin of sector¹

C16: from Late Latin: sector, from Latin: a cutter, from secāre to cut

Example Sentences

One of the most significant risks is the sector’s rapid growth.

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OTTAWA—The Bank of Canada’s No. 2 official endorsed a competition shakeup in the highly concentrated financial-services industry, saying the country’s banking sector is an oligopoly and changes could help lift Canada’s prolonged productivity slump.

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What began as a narrow, tech-driven rally has steadily broadened in 2025, pulling in sectors and stocks that had previously lagged behind or missed out entirely.

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But much of it stems from investors steering clear of a sector overshadowed by politics.

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The leisure and hospitality sector shed 19,000 jobs last month, the largest decline among major sectors, according to ADP.

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Related Words

• district 
• part 
• region 
• zone