sector

American  

[sek-ter] / ˈsɛk tər /

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.

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verb (used with object)

1. to divide into sectors.

sector British  

/ 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

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sector Scientific  

/ sĕk′tər /

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

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Other Word Forms

• sectoral adjective
• subsector noun

Etymology

Origin of sector

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

Example Sentences

Trump said Bondi would soon transition to a new job in the private sector.

From The Wall Street Journal • Apr. 2, 2026

Trump praised her in a post on Truth Social and said she would be "transitioning" to a role in the private sector.

From BBC • Apr. 2, 2026

For investors seeking out safer bets this year, the defensive nature of the wireless sector has held appeal.

From MarketWatch • Apr. 2, 2026

OpenAI has secured the largest private financing in Silicon Valley’s history with commitments of $122 billion in new funding that could boost enthusiasm about artificial intelligence and the technology sector more generally.

From Barron's • Apr. 1, 2026

Yet people managed to move from one sector to the other, day after day, making Berlin the one place on earth where America and Russia—and their spies—came into contact.

From "Spies: The Secret Showdown Between America and Russia" by Marc Favreau

Related Words

• district
• part
• region
• zone