What term describes someone who is accepted as part of a family without any blood relation?

The term that describes someone who is accepted as part of a family without any blood relation is "fictive kin." Fictive kin refers to individuals who are treated as family members but are not biologically related. This concept is significant in understanding family dynamics, especially in diverse social structures where non-biological ties can play an essential role in providing support, emotional connections, and a sense of belonging.

In many cultures, fictive kinship can encompass a wide range of relationships, such as those formed through close friendships, mentorships, or community bonds. This term highlights the importance of social relationships beyond traditional biological family structures, acknowledging that people can form familial ties through shared experiences, love, and mutual care.

The other options relate more specifically to certain types of family relationships. A stepfamily consists of members who are joined by marriage, particularly involving one partner’s children from a previous relationship. An adopted member signifies a formal legal process of joining a family. A close friend may be someone who is very important in someone's life but does not necessarily imply the same level of familial acceptance that fictive kin suggests.