Learner's definition of NUT
1 a : a small dry fruit with a hard shell that grows on trees, bushes, etc.
b : the inside part of a nut that is used as food
The squirrel cracked/opened the nut and ate the meat inside.
walnuts, almonds, peanuts, and other nuts
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
3 a : a crazy or strange person b : a person who is very interested in or enthusiastic about something 4 nuts [plural], informal + impolite : a man's testicles
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.
— nutlike/ˈnʌtˌlaɪk/adjective,[more nutlike; most nutlike]