[uh-sim-uh-ley-shuh-niz-uh m]
  1. the practice or policy of assimilating or encouraging the assimilation of people from all ethnic groups and cultures of origin: In the 1900s, some immigrants at first resisted the assimilationism of the New World.

Origin of assimilationism

First recorded in 1950–55; assimilation + -ism
Related formsas·sim·i·la·tion·ist, noun, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018