Cultural assimilation, or 'assimilation' for short (but that word also has other meanings), is an intense process of consistent integration when members of an ethno-cultural group, typically immigrants, or other minority groups, are "absorbed" into an established, generally larger community, with the intent to change one culture to make them similar to another. This means a loss of all or many characteristics which make the newcomers different. A region or society where assimilation is occurring is sometimes referred to as a "melting pot."
From a historical perspective Assimilation is the process by which an individual or minority group loses its original culture when absorbed into another culture; in the context of colonialism, a policy of total integration of colonies into the colonizing country. It is often remembered as a painful or coercive event.