nuts

1. FOOD a dry brown fruit inside a hard shell, that grows on a tree:
a pine nut
roasted nuts
We were sitting round the fire cracking nuts (=opening them).
2.
TOOL 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.
3. CRAZY PERSON informal someone who is crazy or behaves strangely:
My dad is such a nut.
What are you, some kind of nut?
4. golf/opera etc nut informal someone who is very interested in golf etc ⇨ fanatic:
You don’t have to be a sports nut to enjoy skiing.
5. SEX ORGAN nuts [plural] informal a man’s ↑testicles
6. the nuts and bolts of something informal the practical details of a subject or job:
the nuts and bolts of government
7. tough/hard nut informal someone who is difficult to deal with:
He may have softened a bit in his old age but he’s still a tough nut.
8. a hard/tough nut to crack a difficult problem or situation:
Celtic have lost only once this season and will be a tough nut to crack.
9. be off your nut British English spoken informal to be crazy:
You must be off your nut!
10. do your nut British English spoken to become very angry or worried:
I didn’t get home till three – my mum did her nut!
11. HEAD British English spoken old-fashioned your head or brain
sb’s nut
Oh come on, use your nut!

Oxford Advanced Learner's Dictionary

nut

nut [nut nuts nutted nutting] noun, verb [nʌt] [nʌt]

noun

1. (often in compounds) a small hard fruit with a very hard shell that grows on some trees
• to crack a nut (= open it)
• a Brazil nut
• a hazelnut
• nuts and raisins

see also monkey nut

2. a small piece of metal with a hole through the centre that is screwed onto a bolt to hold pieces of wood, machinery, etc. together
• to tighten a nut

• a wheel nut

3. (BrE, slang) a person's head or brain

4. (BrE also nut·ter) (informal) a strange or crazy person
• He's a complete nut, if you ask me.

see also nuts, nutty

5. (informal) (in compounds) a person who is extremely interested in a particular subject, activity, etc

• a fitness/tennis/computer, etc. nut

6. nuts plural (slang) a man's testicles
more at use a sledgehammer to crack a nut at sledgehammer
Word Origin:
Old English hnutu, of Germanic origin; related to Dutch noot and German Nuss.
Example Bank:
• The documentary focuses on the real nuts and bolts of the film-making process.
• a jar full of nuts and bolts
• nut-allergy sufferers
• I cracked a nut and ate it.
• She is allergic to nuts.
Idioms: do your nut ▪ hard nut ▪ nuts and bolts ▪ off your nut

Derived: nut something out

Cambridge Advanced Learner's Dictionary

nut / nʌt / noun [ C ] (FOOD)

B2 the dry fruit of particular trees that grows in a hard shell and can often be eaten:

a Brazil/cashew nut

Sprinkle some roasted chopped nuts on top.

Collins Advanced Learner’s English Dictionary

nut

[nʌ̱t]
nuts
1) N-COUNT The firm shelled fruit of some trees and bushes are called nuts. Some nuts can be eaten.
→ See also groundnut, hazelnut, peanut
  Nuts and seeds are good sources of vitamin E.
2) N-COUNT A nut is a thick metal ring which you screw onto a metal rod called a bolt. Nuts and bolts are used to hold things such as pieces of machinery together.
  If you want to repair the wheels you just undo the four nuts.
  ...nuts and bolts that haven't been tightened up.
3) N-COUNT: usu with supp If you describe someone as, for example, a football nut or a health nut, you mean that they are extremely enthusiastic about the thing mentioned. [INFORMAL]
  ...a football nut who spends thousands of pounds travelling to watch games.
  Syn:
  fanatic
4) ADJ: v-link ADJ about n (feelings) If you are nuts about something or someone, you like them very much. [INFORMAL]
  They're nuts about the car...
  She's nuts about you.
5) N-COUNT (disapproval) If you refer to someone as a nut, you mean that they are mad. [INFORMAL]
  There's some nut out there with a gun.
6) ADJ: v-link ADJ If you say that someone goes nuts or is nuts, you mean that they go crazy or are very foolish. [INFORMAL]
  You guys are nuts...
  A number of the French players went nuts, completely out of control.
7) N-PLURAL A man's testicles can be referred to as his nuts. [INFORMAL, RUDE]
8) N-COUNT: usu poss N Your head can be referred to as your nut. [INFORMAL]
9) PHRASE: V inflects If someone goes nuts, or in British English does their nut, they become extremely angry. [INFORMAL]
  My father would go nuts if he saw bruises on me...
  We heard your sister doing her nut.
10) PHRASE: usu the PHR of n If you talk about the nuts and bolts of a subject or an activity, you are referring to the detailed practical aspects of it rather than abstract ideas about it.
  He's more concerned about the nuts and bolts of location work.
11) PHRASE: usu v-link PHR If you think someone is difficult to deal with, you can say they are a tough nut or a hard nut. [INFORMAL]
  The Daily Express describes Dr Carey as a pretty tough nut.
12) PHRASE: usu v-link PHR If you say that something is a hard nut to crack or a tough nut to crack, you mean that it is difficult to do or to understand. [INFORMAL]
  Getting out there is in many ways the hardest nut to crack.

Merriam-Webster's Advanced Learner's Dictionary

nut

nut /ˈnʌt/ noun, pl nuts
1 [count]
a : a small dry fruit with a hard shell that grows on trees, bushes, etc.
• The squirrel cracked/opened the nut and ate the meat inside.
• walnuts, almonds, peanuts, and other nuts
- see picture on next page
b : the inside part of a nut that is used as food
• The squirrel sat and ate the nut.
• Are you allergic to nuts?
• a bowl of nuts and raisins
2 [count] : a piece of metal that has a hole through it so that it can be screwed onto a bolt or screw - see picture at carpentry; see also lug nut, wing nut
3 [count] informal
a : a crazy or strange person
• That guy is a real nut.
b : a person who is very interested in or enthusiastic about something
• She's a real baseball/car/health/movie/travel nut.
4 nuts [plural] informal + impolite : a man's testicles
• He got kicked in the nuts.
a hard/tough nut (to crack) : a person or thing that is difficult to deal with, understand, or influence
• The team's defense is a tough nut to crack.
• The problem is a hard nut to crack.
• He's a tough nut, but I think I can get him to agree to the contract.
nuts and bolts : the basic parts or details of an activity, job, etc.
• She's still learning the nuts and bolts of the business.
• Tell me what the nuts and bolts of the plan involve.
soup to nuts
- see ¹soup
- nut·like /ˈnʌtˌlaɪk/ adj [more ~; most ~]
• The cake had a nutlike [=nutty] taste.