Sentence:  Nor have we remembered that in the <WSD>melting</WSD> pot of America the hundreds of isolated and semi isolated ethnic , regional and occupational groups did not fuse into a homogeneous national unit until long after education and industrialization had caused them to cast oral tradition aside as a means of carrying culturally significant material . 
Meaning of the word marked with <WSD> tags:  an environment in which many ideas and races are socially assimilated