Meaning of MAIN in English
I. main 1 S1 W1 /meɪn/ BrE AmE adjective [only before noun]
[ Language: Old English ; Origin: mægen- , from mægen 'strength' ]
1 . larger or more important than all other things, ideas etc of the same kind:
The main reason for living in Spain is the weather.
What do you consider to be the main problem?
Our main concern is that the children are safe.
a summary of the main points of the agreement
the main aim of the meeting
I’ll meet you outside the main entrance.
the main bedroom
2 . the main thing spoken used to say what is the most important thing in a situation:
As long as you’re not hurt, that’s the main thing.
The main thing is not to panic.
⇨ an eye for/on/to the main chance at ↑ eye 1 (22)
• • •
▪ main larger or more important than all the others:
the main entrance of the building
the main reason for his decision
▪ chief/principal most important. Chief and principal are more formal than main , and are often used in written English:
Coffee is the country’s principal export.
What is the company’s chief objective?
▪ major very important or serious:
Smoking is a major cause of heart disease.
Street crime is becoming a major problem.
▪ key most important, or the one that everything or everyone else depends on:
Education is likely to be a key issue in the election campaign.
Hooper was a key member of the team.
Diet is key.
▪ number one especially spoken most important or best - this phrase sounds a little informal and it is used especially in spoken English:
Reliability is the number one priority.
the number one cause of death
He is still in the number one position.
▪ primary most important - used especially about the most important aim, role, cause, or concern. Primary is more formal than main :
The primary aim of the project was to help students develop their communication skills.
Security is our primary concern.
The primary function of the university was considered to be the teaching of ‘the great cultural disciplines’.
▪ prime very important or most important - used especially about the most important reason, cause, or aim, or about the most likely ↑ target or ↑ suspect . Prime is more formal than main :
Their prime objective is to increase profits for their shareholders.
Tourists are prime targets for theft and robbery.
▪ core most important - used especially about the things that people should pay most attention to:
the core skills of reading and writing
He wants the company to focus on its core business - advertising.
The party’s core values are individual freedom and reducing the amount of government bureaucracy.
▪ central most important and having more influence than anything else:
The U.S. played a central role in the peace negotiations.
a central theme of the book
The central question is, why are people still so attached to their cars?
▪ predominant most common, typical, or important:
Yellow was the predominant colour everywhere.
High arched windows are a predominant feature in English churches.
New York still has a predominant role in the contemporary art world.
II. main 2 BrE AmE noun
1 . [countable] a large pipe or wire carrying the public supply of water, electricity, or gas:
The report found that many of Yorkshire’s water mains needed replacing.
a burst gas main
2 . British English
a) the mains the place on a wall where you can connect something to a supply of electricity:
You can run the torch off batteries or plug it into the mains.
at the mains
Make sure that the television is turned off at the mains.
b) mains gas/water/electricity gas, water, or electricity supplied to a building through a pipe or wire:
The heater will run off mains gas or bottled gas.
3 . in the main mostly:
Their job in the main consisted of cleaning and maintaining the building.
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012