| Term | Definition |
| Expansion Diffusion | An innovation or idea develops in a source area and remains strong there while it spreads. |
| Contagoius Diffusion | A type of expansion diffusion- affects nearly all adjacent populations. |
| Hierarchical Diffusion | A type of expansion diffusion- affects only those who are susceptible. |
| Stimulus Diffusion | A type of expansion diffusion- spread of an underlying principle/action/reaction (much like the Enlightenment) |
| Relocation Diffusion | Spread of ideas/ innovation through the migration of people |
| Migrant Diffusion | A type of relocation diffusion- when an idea or innovation originates somewhere & enjoys a strong but brief adoption there (much like the Spanish Flu) |
| Acculturation | Less dominant culture adopts cultural traits of a more distinct culture, but both remain distinct. |
| Transculuturation | Cultural traits are shared; both function as sources and adopters. |
| Assimilation | Process where one society adopts cultural traits over time after coming into contact w/ another culture. |