hat is a head covering which is worn for various reasons, including protection against weather conditions, ceremonial reasons such as university graduation, religious reasons, safety, or as a fashion accessory.
The term "hat" also refers to:
1. In baseball, the batter's, catcher's, and umpire's headgear
2. A person's role or position ("wearing many hats")
3. Slang for "expert" or "professional" ("he's a real hat at coding")
4. In magic tricks, the magician's hat used for pulling out rabbits