dif|fu|sion|ism «dih FYOO zhuh nihz uhm», noun.
any theory that emphasizes diffusion, especially the theory that different cultures arise by diffusion from a single source: »
Most archaeologists were schooled in…diffusionism. This notion holds that civilization and advanced technology arose in Egypt and the Middle East and then, starting about 2500 B.C., diffused, or flowed, northward into Europe (Robert C. Cowen).
Useful english dictionary. 2012.