1. （组织之间的）密切联系，隶属关系
If one group has an affiliation with another group, it has a close or official connection with it.

2. （个人之间或个人与组织之间的）联系，从属关系
If you have an affiliation with a group or another person, you have a close or official connection with them.

1. the act of becoming formally connected or joined

e.g. welcomed the affiliation of the research center with the university

2. a social or business relationship

e.g. a valuable financial affiliation
he was sorry he had to sever his ties with other members of the team
many close associations with England

Synonym: associationtietie-up