Frequency: The word is one of the 700 most common words in English.
1.
You use why in questions when you ask about the reasons for something.
Why hasn't he brought the whisky?...
Why didn't he stop me?...
'I just want to see him.'-'Why?'...
Why should I leave?
QUEST
2.
You use why at the beginning of a clause in which you talk about the reasons for something.
He still could not throw any further light on why the elevator could have become jammed...
Experts wonder why the US government is not taking similarly strong actions against AIDS in this country...
I can't understand why they don't want us.
CONJ
•
Why is also an adverb.
I don't know why...
It's obvious why...
Here's why.
ADV: ADV after v, be ADV
3.
You use why to introduce a relative clause after the word 'reason'.
There's a reason why women don't read this stuff; it's not funny...
Unless you're ill, there's no reason why you can't get those 15 minutes of walking in daily.
PRON
•
Why is also an adverb.
He confirmed that the city had been closed to foreigners, but gave no reason why.
ADV: n ADV
4.
You use why with 'not' in questions in order to introduce a suggestion.
Why not give Claire a call?...
Why don't we talk it through?
QUEST
5.
You use why with 'not' in questions in order to express your annoyance or anger.
Why don't you look where you're going?...
Why don't they just leave it alone?
QUEST [feelings]
6.
You say why not in order to agree with what someone has suggested.
'Want to spend the afternoon with me?'-'Why not?'...
CONVENTION [formulae]
7.
People say 'Why!' at the beginning of a sentence when they are surprised, shocked, or angry. (mainly AM)
Why hello, Tom...
EXCLAM [feelings]
8.