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• main
  main

  adjective

  chief in size, extent, or importance; principal; leading.
• Main
  Main

  noun

  a river in central and W Germany, flowing W from the Bohemian Forest in N Bavaria into the Rhine at Mainz. 305 miles (490 km) long.

main

¹ American  

[meyn] / meɪn /

adjective

1. chief in size, extent, or importance; principal; leading.

   the company's main office;

   the main features of a plan.

   Synonyms:

   capital, primary, paramount, prime, cardinal

   Antonyms:

   least, secondary

2. sheer; utmost, as strength or force.

   to lift a stone by main force.

   Synonyms:

   unqualified, pure

3. of or relating to a broad expanse.

   main sea.

4. Grammar. syntactically independent; capable of use in isolation.

5. Nautical.

   1. of or relating to a mainmast.

   2. noting or pertaining to a sail, yard, boom, etc., or to any rigging belonging to a mainmast.

   3. noting any stay running aft and upward to the head of a mainmast.

      main topmast stay.

6. Obsolete.

   1. having or exerting great strength or force; mighty.

   2. having momentous or important results; significant.

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noun

1. a principal pipe or duct in a system used to distribute water, gas, etc.

   Synonyms:

   conduit

2. physical strength, power, or force.

   to struggle with might and main.

   Synonyms:

   might

   Antonyms:

   weakness

3. the chief or principal part or point.

   The main of their investments was lost during the war.

4. Literary. the open ocean; high sea.

   the bounding main.

5. the mainland.

6. Usually mains a main course in a meal.

   The restaurant offers four mains: one chicken, two beef, and one fish.

adverb

1. South Midland U.S. (chiefly Appalachian). very; exceedingly.

   The dogs treed a main big coon.

verb (used with or without object)

1. Slang. mainline.

idioms

1. in the main, for the most part; chiefly.

   In the main, the novel was dull reading.

main ² American  

[meyn] / meɪn /

noun

1. a cockfighting match.

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Main ³ American  

[meyn, mahyn] / meɪn, maɪn /

noun

1. a river in central and W Germany, flowing W from the Bohemian Forest in N Bavaria into the Rhine at Mainz. 305 miles (490 km) long.

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main ¹ British  

/ meɪn /

adjective

1. chief or principal in rank, importance, size, etc

2. sheer or utmost (esp in the phrase by main force )

3. nautical of, relating to, or denoting any gear, such as a stay or sail, belonging to the mainmast

4. obsolete significant or important

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noun

1. a principal pipe, conduit, duct, or line in a system used to distribute water, electricity, etc

2. (plural)

   1. the main distribution network for water, gas, or electricity

   2. ( as modifier )

      mains voltage

3. the chief or most important part or consideration

4. great strength or force (now chiefly in the phrase ( with ) might and main )

5. literary the open ocean

6. archaic short for Spanish Main

7. archaic short for mainland

8. on the whole; for the most part

main ² British  

/ meɪn /

noun

1. a throw of the dice in dice games

2. a cockfighting contest

3. a match in archery, boxing, etc

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Main ³ British  

/ meɪn, main /

noun

1. a river in central and W Germany, flowing west through Würzburg and Frankfurt to the Rhine. Length: about 515 km (320 miles)

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main More Idioms  

More idioms and phrases containing main

• eye to the main chance
• in the main
• might and main

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Etymology

Origin of main¹

First recorded before 900; Middle English noun main(e), mayn(e) “strength, power,” Old English mægen, megen, cognate with Old Norse magn, megin, megn “strength”; Middle English adjective main(e), partly from Old Norse megin-, megn “strong,” partly from Old English noun mægen used in compounds, as in mægen-weorc “mighty work”

Origin of main²

First recorded in 1560–70; origin uncertain; perhaps special use of main ¹; compare main chance

Explanation

When you describe something as main, you mean it's the most important, well-known, or biggest of its kind. The main branch of the post office in a city is usually the largest and busiest. The main theme of your English paper is your thesis, the basic, fundamental thing you're trying to express in your writing. The main road in town is the most busy and populated — in fact, in many places this road is called "Main Street." This adjective describes things that stand out as the most important or prominent in their category. In the thirteenth century, it meant "large or strong," and came from the Old English mægen, "power, strength, or force."

Example Sentences

But all the Enhanced Games athletes who BBC Sport spoke to when granted access to the training camp in February said money was their main motivation and felt they had been underpaid during their careers.

From BBC • May 20, 2026

Meanwhile, the labor market has stayed resilient, removing one of the main arguments for keeping rates steady or lowering them further.

From Barron's • May 20, 2026

Researchers first photographed it in 2003 at Brazil's Abrolhos Bank, the country's main humpback whale nursery off the coast of Bahia.

From Science Daily • May 20, 2026

At the time, it was was assumed that Lopez would be making the home her main residence.

From MarketWatch • May 20, 2026

“We’re half a block from the main police headquarters. And yet I don’t know where else to suggest.”

From "The Hiding Place" by Corrie ten Boom

Related Words

• central
• essential
• fundamental
• leading
• major
• particular
• preeminent
• primary
• prime
• special
• vital