Frequency: The word is one of the 700 most common words in English.
1.
You use ~ 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 ~ at the beginning of a clause in which you talk about the reasons for something.
He still could not throw any further light on ~ the elevator could have become jammed...
Experts wonder ~ the US government is not taking similarly strong actions against AIDS in this country...
I can’t understand ~ they don’t want us.
CONJ
•
Why is also an adverb.
I don’t know ~...
It’s obvious ~...
Here’s ~.
ADV: ADV after v, be ADV
3.
You use ~ to introduce a relative clause after the word ‘reason’.
There’s a reason ~ women don’t read this stuff; it’s not funny...
Unless you’re ill, there’s no reason ~ 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 ~.
ADV: n ADV
4.
You use ~ 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 ~ 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 ~ 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.
the ~s and wherefores: see wherefores