Why is fixing a fractured bone called reducing the fracture?

Fixing a fractured bone is called "reduction" because during realignment, all components have to be put back to their ideal anatomical (physiological) relationships; this process often restores (reduces) the size or complexity of the affected region, hence the medical term.

"Reduction" in medical terminology simply means that the dislocated, disjointed, displaced, protruded, slipped, twisted, deformed or herniated part or organ is put back to its normal anatomical structure and location.