Learner's definition of ASSIMILATE
to learn (something) so that it is fully understood and can be used
to cause (a person or group) to become part of a different society, country, etc.
to adopt the ways of another culture
to fully become part of a different society, country, etc.
to adopt (something) as part of a larger thing
The language is constantly assimilating new words. [=making new words part of itself; the language is constantly getting new words]
Many of these religious traditions have been assimilated into the culture.