Tra từ main - Từ điển Oxford Advanced Learner 8th

main [main mains] adjective, noun BrE [meɪn] NAmE [meɪn]
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.
see with an eye for/on/to the main chance at ↑eye _n.

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’.

Thesaurus:
main adj. only before noun
•Health and safety is our main concern.
major • • key • • chief • • leading • • central • • principal • • prime • • primary • • predominant • |informal number one •
Opp: secondary, Opp: minor
a/the main/major/key/chief/central/principal/prime/primary/predominant/number one concern
a/the main/major/key/chief/central/principal/prime/primary aim/focus/function/objective/task/reason
a/the main/major/key/leading/central/principal role
main/major/principal road/town/city

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.
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.
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.
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.
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.
a/the main/major/key/central/principal/chief/prime aim/concern
a/the main/major/principal road/town/city
the main/key thing is to…
to be of major/key/central/prime importance

Example Bank:
•Please use the main entrance.
•The main course was roast lamb.
•The main thing is to remain calm.
Idiom: ↑in the main

noun
1. countable 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 mainsplural (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

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’.

Example Bank:
•Some of the remoter houses in the town are not on the mains.
•The main serves four towns.
•There's a burst water main in Quarry Road.
•They're laying a new gas main through the town.
•Turn the water off at the mains.
•an island without mains electricity
•water damage from broken mains
•The area was evacuated after the discovery of a leaking gas main.