What term is used to describe someone who has been formally placed into a group?

The term used to describe someone who has been formally placed into a group is "inducted." This term typically refers to a formal process where individuals are officially brought into a group or organization, often accompanied by a ceremony or specific procedures that signify their new status. Induction is often used in various contexts, such as membership in societies, organizations, or even the military, highlighting a structured and acknowledged entry into the group.

While "initiated" can also imply entering a group often with ritualistic connotations, it doesn't necessarily carry the formal aspect that "inducted" does. "Appointed" generally refers to being assigned to a position with specified responsibilities rather than merely joining a group. Similarly, "accepted" indicates a more informal acknowledgment into a group rather than the formal and ceremonial process indicated by "inducted." Therefore, "inducted" best captures the concept of formally being placed into a group.