A Raisin in the Sun
An assimilationist is someone who tries to assimilate, or blend in with, the dominant culture, usually at the expense his/her own native culture. To an extent, all people are assimilationists because everyone wants to fit in with other people.
Remaineder of question. Why, then, does Beneatha get so angry when Asagai hints that she is an assimilationist? A Raisin In The Sun Packet Questions cite if needed