What is great niece?

A great niece is the daughter of one's niece or nephew. She is the child of one's nephew or niece, making her the grandchild of one's sibling. In other words, the great niece is the grandchild of your brother or sister. The term great niece is used to describe the familial relationship between an aunt or uncle and the child of their niece or nephew. The great niece is considered to be a part of the extended family and is often loved and cared for by her aunt and uncle as a member of the family.