/ meɪn; NAmE / adjective , noun
■ adjective
[ only before noun ] being the largest or most important of its kind :
Be careful crossing the main road .
the main course (= of a meal)
We have our main meal at lunchtime.
Reception is in the main building.
Poor housing and unemployment are the main problems.
The main thing is to stay calm.
•
IDIOMS
see eye noun
■ noun
1.
[ C ] a large pipe that carries water or gas to a building; a large cable that carries electricity to a building :
a leaking gas main
—see also water main
2.
a large pipe that carries waste / water and sewage (= human waste, etc.) away from a building
3.
the mains [ pl. ] ( BrE ) the place where the supply of water, gas or electricity to a building or an area starts; the system of providing gas, water and electricity to a building or of carrying it away from a building :
The house is not yet connected to the mains.
The electricity supply has been cut off at the mains .
Plug the transformer into the mains (= the place on a wall where electricity is brought into a room) .
mains gas / water / electricity
The shaver will run off batteries or mains.
mains drainage
•
IDIOMS
- in the main
••
SYNONYMS
main
major ♦ key ♦ central ♦ principal ♦ chief ♦ prime
These words all describe sb/sth that is the largest or most important of its kind.
main
[only before noun] largest or most important:
Be careful crossing the main road.
•
The main thing is to remain calm.
major
[usually before noun] very large or important:
He played a major role in setting up the system.
NOTE
Major is most often used after a with a singular noun, or no article with a plural noun. When it is used with the or my / your / his / her / our / their it means 'the largest or most important':
Our major concern here is combatting poverty.
In this meaning it is only used to talk about ideas or worries that people have, not physical things, and it is also more formal than main : Be careful crossing the major road. • The major thing is to remain calm.
key
[usually before noun] most important; essential:
He was a key figure in the campaign.
NOTE
Key is used most frequently in business and political contexts. It can be used to talk about ideas, or the part that sb plays in a situation, but not physical things. It is slightly more informal than major , especially when used after a noun and linking verb:
Speed is key at this point.
central
( rather formal ) most important:
The central issue is that of widespread racism.
NOTE
Central is used in a similar way to key , but is more formal. It is most frequently used in the phrase sth is central to sth else .
principal
[only before noun] ( rather formal ) most important:
The principal reason for this omission is lack of time.
NOTE
Principal is mostly used for statements of fact about which there can be no argument. To state an opinion, or to try to persuade sb of the facts as you see them, it is more usual to use key or central :
The key / central issue here is...
chief
[only before noun] ( rather formal ) most important:
Unemployment was the chief cause of poverty.
prime
[only before noun] ( rather formal ) most important; to be considered first:
My prime concern is to protect my property.
PATTERNS AND COLLOCATIONS :
a/the main / major / key / central / principal / chief / prime aim / argument
a/the main / major / key / central / principal / chief / prime concern / problem
a/the main / major / key / principal / chief drawback / worry
a/the main / major / principal road / town / city
the main / principal speaker / building / entrance
the main / key thing is to...
to be of major / key / central / prime importance
••
WORD ORIGIN
Middle English : from Old English mægen physical force , reinforced by Old Norse meginn , megn strong, powerful, both from a Germanic base meaning have power.