Main

UK: 'main': /ˈmeɪn/; 'Main': English: /meɪn/, German: /main/

US: /meɪn/

US: 'main': (mān); 'Main': (mān; Ger. mīn)

Collins Concise English Dictionary © HarperCollins Publishers::

Main / 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)

WordReference Random House Learner's Dictionary of American English © 2026

main¹ /meɪn/   adj. [before a noun]

1. chief in size, extent, or importance:
   He had the main part in a play.
2. Grammar (in a sentence) of or relating to the clause that can stand by itself;
   independent:
   In the sentence I'll see you when I get home, the main clause is I'll see you. 

n. [countable]

3. Civil Engineering a principal pipe in a system used to carry and send water, gas, etc.

Idioms

4. in the main, most importantly:
   In the main, she has proposed a very good plan.
5. with might and main, with strength or force.

main•ly, adv. 

: He got rich mainly from government contracts.

WordReference Random House Unabridged Dictionary of American English © 2026

main¹  (mān), adj. 

1. chief in size, extent, or importance;
   principal;
   leading:
   the company's main office; the main features of a plan.
2. sheer;
   utmost, as strength or force:
   to lift a stone
   by main force.
3. of or pertaining to a broad expanse:
   main sea.
4. Grammar syntactically independent;
   capable of use in isolation. Cf. dependent (def. 4), independent (def. 14), main clause. 
5. [Naut.]
   • Nautical of or pertaining to a mainmast.
   • Nautical noting or pertaining to a sail, yard, boom, etc., or to any rigging belonging to a mainmast.
   • Nautical noting any stay running aft and upward to the head of a mainmast:
     main topmast stay.
6. [Obs.]
   • having or exerting great strength or force;
     mighty.
   • having momentous or important results;
     significant.

n. 

7. Civil Engineering a principal pipe or duct in a system used to distribute water, gas, etc.
8. physical strength, power, or force:
   to struggle with might and main.
9. the chief or principal part or point:
   The main of their investments was lost during the war.
10. [Literary.] the open ocean;
    high sea:
    the bounding main.
11. the mainland.
12. Idioms in the main, for the most part;
    chiefly:
    In the main, the novel was dull reading.

adv. 

13. Dialect Terms [South Midland U.S.] (chiefly Appalachian). very;
    exceedingly:
    The dogs treed a main big coon.

v.i., v.t. 

14. Slang Terms mainline.

• Old Norse megenn, megn strong, partly independent use of Old English mægen (noun, nominal) taken as an adjective, adjectival in compounds, as in mægen-weorc, literally, work of might
• bef. 900; (noun, nominal) Middle English meyn, mayn strength, power, Old English mægen, cognate with Old Norse megin(n), megn strength; (adjective, adjectival) Middle English mayn, partly

Synonyms

• 1. cardinal, prime, paramount, primary, capital.
• 2. pure, direct.
• 7. conduit.
• 8. might.

Antonyms

• 1. secondary, least.
• 8. weakness.

main²  (mān), n. 

1. a cockfighting match.

• 1560–70; perh. special use of main¹; compare main chance

Main  (mān; Ger. mīn), n. 

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

Collins Concise English Dictionary © HarperCollins Publishers::

main / meɪn/ adjective (prenominal)

1. chief or principal in rank, importance, size, etc
2. sheer or utmost (esp in the phrase by main force)
3. of, relating to, or denoting any gear, such as a stay or sail, belonging to the mainmast

noun

1. a principal pipe, conduit, duct, or line in a system used to distribute water, electricity, etc
2. (plural) the main distribution network for water, gas, or electricity
3. (as modifier): mains voltage
4. the chief or most important part or consideration
5. great strength or force (now chiefly in the phrase (with) might and main)
6. the open ocean
7. 
   short for Spanish Main
8. 
   short for mainland
9. in the main, for the main ⇒ on the whole; for the most part

Etymology: 13th Century: from Old English mægen strength

main / meɪn/ noun

1. a throw of the dice in dice games
2. a cockfighting contest
3. a match in archery, boxing, etc

Etymology: 16th Century: of unknown origin