least and fewest
the least as determiner: superlative of little
The least can be used as a determiner before uncountable nouns; it is the superlative of little (= not much, (see here), and the opposite of the most.
- I think I probably do the least work in this office.
The least can be used without a noun if the meaning is clear.
- Jess earns the most money in our family; Dan earns the least.
We use the least of before plural abstract nouns to mean ‘the smallest of’.
- ‘What will your mother think?’ ‘That’s the least of my worries.’
‘any … at all’
With singular abstract nouns, the least can mean ‘any … at all’.
- Do you think there’s the least chance of Smith winning the election?
- ‘What’s the time?’ ‘I haven’t got the least idea.’
the fewest as determiner: superlative of few
The fewest can be used before plural nouns as the superlative of few (see here).
- The translation with the fewest mistakes isn’t always the best.
Least is often used instead of fewest before plural nouns (… the least mistakes), especially in an informal style. Some people feel this is incorrect.
For other uses of least, search the Index.
(the) least with adjectives: the opposite of (the) most or (the) …est
(The) least is used before adjectives in the same way as (the) most or (the) …est (see here), but with the opposite meaning.
- The least expensive trips are often the most interesting.
- I’m least happy when I have to work at weekends.
For the use of the with superlatives, (see here).
least as adverb
Least can be used as an adverb (the opposite of most).
- She always arrives when you least expect it.
- I don’t much like housework, and I like cooking least of all.
at least
At least means ‘not less than (but perhaps more than)’.
- ‘How old do you think he is?’ ‘At least thirty.’
- He’s been in love at least eight times this year.
We can also use at least as a discourse marker (see here) to suggest that one thing is certain or all right, even if everything else is unsatisfactory.
- We lost everything in the fire. But at least nobody was hurt.
not in the least
We can use not in the least in a formal style to mean ‘not at all’, especially when talking about personal feelings and reactions.
- I was not in the least upset by her bad temper.
For less and fewer, (see here).