What Do You Call Your Mother's Cousin?

The first cousin of one's mother is referred to as one's first cousin, once removed. This phrase is also used to denote one's relationship with a first cousin's child. The phrase "once removed" specifies that there is one generation difference between the two relatives, while "twice removed" signifies members of a family that are two generations apart.

In terms of relationships between cousins, first cousins share a set of grandparents that can be either on one's mother or father's side. A person can also have second, third and fourth cousins. However, the difference between second and third cousins is that second cousins share a set of great-grandparents while third cousins are related through one set of great-great-grandparents.