sector

American  

[sek-ter] / ˈsɛk tər /

noun

sectors plural

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

Derived Forms

• subsector
  noun
• sectoral
  adjective

Inflected Forms

Nouns

• sectors
  plural

Etymology

Origin of sector

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

Explanation

Sector sounds like section, doesn't it? That's a good way to remember that a sector is a specific part of society or the economy, made up of similar elements — like the health care sector or the education sector. Our most common use of the word sector refers to a society’s divisions. For example, our economy is divided into the private sector (privately-owned interests) and the public sector (government). Other than that, the word also has many technical applications in math and science. From the Latin verb secare, "to cut," sector was applied long ago to math as a section of a circle, which carried through to military language as "a circle around a headquarters."

Example Sentences

See Examples For:

sector sectors

The rally gained further traction as surging energy prices and broader AI momentum lifted the sector.

From The Wall Street Journal ● Jul. 28, 2026

Harmantas said the declines "also reflect broader valuation concerns" in the technology sector.

From Barron's ● Jul. 28, 2026

Sentiment toward the semiconductor sector was hit by a report that a Chinese state-backed company began mass-producing chip-making equipment.

From The Wall Street Journal ● Jul. 28, 2026

SpaceX is set to report earnings for the first time as a public company next Tuesday — potentially setting the sector up for a fresh bout of volatility.

From MarketWatch ● Jul. 28, 2026

Causey was a master of half expression, half smiles, and half glowers, for all nuances of expression stopped at the invisible frontier that marked the dead sector of his face.

From "The Great Santini" by Pat Conroy

He said he’s reaching out to different sectors of the community, including Black organizations and churches.

From Los Angeles Times ● Jul. 28, 2026

—European stock indexes gained as the sharp fall in oil prices prompts gains across all sectors except energy.

From The Wall Street Journal ● Jul. 27, 2026

Most large companies are expected to continue with quarterly reporting while some companies won’t, leading to differences within individual sectors.

From The Wall Street Journal ● Jul. 26, 2026

But he also sees the breakdown as creating some opportunities, as it leads to “a more defensive rotation” into sectors showing some technically bullish tendencies.

From MarketWatch ● Jul. 26, 2026

In both sectors, the attacks were preceded by the discharge of chlorine gas—the first time poison gas had been used by the Allies.

From "The War to End All Wars: World War I" by Russell Freedman

Related Words

• district
• part
• region
• zone