Other forms: extended families
Your extended family is everyone who's related to you besides your parents, siblings, or children. Aunts, great-grandparents, nephews, second cousins: these are all part of your extended family.
Extended family, coined in 1942, was originally a term used by sociologists. Rather than just a generic way to talk about family members outside of parents and children, its earliest use was for multi-generational households. If your grandmother and uncle live with you, together you're an extended family. If you're not a sociologist, you’re more likely to describe the group composed of your great-aunt, your cousin, and your sister-in-law as your extended family.