Final answer:
In geography, Diffusion is the process by which a cultural trait, idea, or innovation is transmitted from one region or person to another over time.
Step-by-step explanation:
The definition of "Diffusion" in geography is the process of spread of a feature or trend from one place to another over time. It relates to how cultural traits, technologies, or ideas move through populations and territories. A common example that illustrates diffusion in human geography is the spread of a religion, such as Islam, which expanded through both expansion diffusion and relocation diffusion, making it one of the most followed religions globally. In a more scientific context, diffusion refers to the movement of molecules from an area of high concentration to an area of low concentration until the concentration is uniform, which also can describe the spread of cultural elements within a societal context.