Arc is a curved line or shape, like part of a circle. When you throw a ball, it travels through the air in an arc, rising up and then falling back down in a smooth curve. A rainbow forms a colorful arc across the sky. Architects use arcs in bridges and doorways because the curved shape is both beautiful and strong.

The word also describes the path of a story or a person's journey over time. When teachers talk about a character's arc in a novel, they mean how that character changes from beginning to end. In The Lion, the Witch and the Wardrobe, Edmund has a clear arc: he starts out selfish and betrays his siblings, but through his experiences, he becomes brave and loyal.

You might hear someone say a person's career followed an arc, meaning it had a shape to it: rising success, perhaps a peak, and maybe challenges later. Like the curved path of a thrown ball, a story arc or life arc has a trajectory that you can trace and understand.