Nut

noun
  1. A hard-shelled dry fruit or seed with a separable rind or shell and interior kernel, often edible. noun
    She cracked open the nut to eat the kernel inside.
    Almonds are a type of nut that is often used in baking.
  2. A small metal block, usually square or hexagonal, with a hole through the center for screwing onto a bolt as a fastener. noun
    He tightened the nut to secure the bolt in place.
    Make sure the nut is properly aligned with the bolt thread.
  3. A person who is very enthusiastic about or devoted to a particular interest or activity; a fanatic. noun
    She's a real movie nut and watches films every weekend.
    He's a fitness nut who spends hours at the gym every day.
  4. A slang term for a crazy or eccentric person. noun
    Don't mind him, he's just a harmless nut.
    She acts like a nut sometimes, but she's really nice.
  5. The amount of money necessary to operate a business or maintain a lifestyle. noun
    He needs to make enough to cover his monthly nut.
    The company's nut is too high for its current revenue.