The term "color line" refers to the racial boundary or segregation between different racial groups. Some synonyms for the term could be "racial divide," "segregation," "discrimination," "prejudice," and "bias." These words all describe the same concept of racial separation based on physical appearance. Other synonyms that capture the negative connotation of the term could include "bigotry," "racism," "intolerance," and "separatism." These words all indicate a form of hostility or discrimination towards people of different races. While these terms have been used in the past to describe the racial tensions and segregation in society, they serve as a reminder of the importance of inclusivity and acceptance in modern-day society.