An extreme form of excommumincation and shunning practiced by several American-based Christian sects such as Jehovah’s Witnesses and Mormons.
Generally, disfellowshipped people are not allowed to even even say ‘hello’ to their former friends and family still in the religion. If a member of the religion chooses to associate with a disfellowshipped person, they risk being disfellowshipped themselves for doing so. Depending on the strictness of the local elders, a parent may even be disfellowshipped for associating with their disfellowshipped minor child.