nutter
/ˈnʌtər/
noun
- A person who is crazy, eccentric, or behaves in a very strange way.
- My neighbor is a bit of a nutter—he talks to his plants for hours.
- Don't listen to that nutter; his ideas make no sense at all.
- Some nutter tried to jump off the bridge yesterday.
- A person who is extremely enthusiastic or obsessed with something.
- He's a total fitness nutter who goes to the gym twice a day.
- She's a gardening nutter and spends every weekend in her greenhouse.
- My brother is a train nutter and can name every locomotive model.
Synonyms