nut1 S3 [countable]
a dry brown fruit inside a hard shell, that grows on a tree:
a pine nut
We were sitting round the fire cracking nuts (=opening them).
a small piece of metal with a hole through the middle which is screwed onto a bolt to fasten things together:
Use a wrench to loosen the nut.
someone who is crazy or behaves strangely:
My dad is such a nut.
What are you, some kind of nut?
someone who is very interested in golf etc [↪ fanatic]:
You don't have to be a sports nut to enjoy skiing.
a man's testicles
sex organ[plural] informal
the practical details of a subject or job:
the nuts and bolts of government
someone who is difficult to deal with:
He may have softened a bit in his old age but he's still a tough nut.
a difficult problem or situation:
Celtic have lost only once this season and will be a tough nut to crack.
9 British English spoken informal
to be crazy:
You must be off your nut!
10 British English spoken
to become very angry or worried:
I didn't get home till three - my mum did her nut!