less
used in front of nouns
You use less in front of an uncountable noun to say that one quantity is not as big as another, or that a quantity is not as big as it was before.
A shower uses less water than a bath.
His work gets less attention than it deserves.
Less is sometimes used in front of plural nouns.
This proposal will mean less jobs.
Less people are going to university than usual.
Some people think this use is wrong. They say that you should use fewer in front of plural nouns, not ‘less’.
There are fewer trees here.
The new technology allows products to be made with fewer components than before.
However, fewer sounds formal when used in conversation. As an alternative to ‘less’ or ‘fewer’, you can use not as many or not so many in front of plural nouns. These expressions are acceptable in both conversation and writing.
There are not as many cottages as there were.
There aren't so many trees there.
After not as many and not so many you use as, not ‘than’.
‘less than’ and ‘fewer than’
You use less than in front of a noun phrase to say that an amount or measurement is below a particular point or level.
It's hard to find a house in Beverly Hills for less than a million dollars.
I travelled less than 3000 miles.
Less than is sometimes used in front of a noun phrase referring to a number of people or things.
The whole of Switzerland has less than six million inhabitants.
The country's army consisted of less than a hundred soldiers.
Some people think this use is wrong. They say that you should use fewer than, not ‘less than’, in front of a noun phrase referring to people or things.
He had never been in a class with fewer than forty children.
In 1900 there were fewer than one thousand university teachers.
You can use less than in conversation, but you should use fewer than in formal writing.
However, fewer than can only be used when the following noun phrase refers to a number of people or things. Don't use ‘fewer than’ when the noun phrase refers to an amount or measurement. Don't say, for example, `I travelled fewer than 3000 miles.
‘less’ used in front of adjectives
Less can be used in front of an adjective to say that someone or something has a smaller amount of a quality than they had before, or a smaller amount than someone or something else has.
After I spoke to her, I felt less worried.
Most of the other plays were less successful.
Be careful
Don't use ‘less’ in front of the comparative form of an adjective. Don't say, for example, ‘It is less colder than it was yesterday’. Say ‘It is less cold than it was yesterday’.
Don't use ‘less’ in front of the comparative form of an adjective. Don't say, for example, ‘It is less colder than it was yesterday’. Say ‘It is less cold than it was yesterday’.
‘not as ... as’
In conversation and informal writing, people don't usually use ‘less’ in front of adjectives. They don't say, for example, ‘It is less cold than it was yesterday’. They say ‘It is not as cold as it was yesterday’.
The region is not as pretty as the Dordogne.
Not so is also sometimes used, but this is less common.
The officers here are not so young as the lieutenants.
After not as and not so, you use as, not ‘than’.