Headcanon. Noun. In the context of fandoms, a headcanon is a personal interpretation or belief about a fictional story that's not part of the "official" canon. It's essentially what a fan imagines or wants to be true about a story, filling in details not explicitly stated in the original work. Furthermore headcanons can range from simple details like a character's favorite color or food to more complex ideas about backstory, what happens after the story ends, or even alternative relationships between characters (shipping)