Grandparent
For example: Bob has a son named Rick. Rick, in turn, has 2 children; a boy (Bill) and a girl (Mary). Bob is the grandfather (male grandparent) of both Bill and Mary. Bill is the grandson (male grandchild) of Bob, and Mary is the granddaughter (female grandchild) of Bob. Rick's mother would be the grandmother (female grandparent) of both Mary and Bill.