Spread: Spread refers to how something extends or covers a larger area over time. It can describe how ideas, diseases, cultures, or languages expand from their origin.
Dominance: Dominance refers to having power or control over others. In this context, it relates to the influence that Arabic language gained over other languages in North Africa and the Middle East during its proliferation.
Assimilation: Assimilation is when individuals adopt new cultural customs and practices while abandoning their own. During Arabic's proliferation, some communities assimilated by adopting Arabic as their primary language.