George herbert mead used the term to refer to those with whom children have a close affiliation.

The answer is significant other. The term “significant other” was invented by Harry Stack Sullivan, who recognized significant others as those who openly mingle the person to whom they are significant. While, Sullivan (1940) and George Herbert Mead (1967) propose that socialization depend on upon a person's seeing the other's view of himself or herself as significant or important. Significant others are those persons who are of necessary importance in an individual's life to touch the individual’s emotions, sense of self, and behavior.