Cousin (or First Cousin or Full Cousin) The son or daughter of an uncle or aunt. People who have the same grandparents, but not the same parents.
Second Cousin People who share a set of great-grandparents, but do not have the same grandparents.
Third, Fourth, and Fifth Cousins Third cousins share a set of great-great-grandparents, but not the same great-grandparents. Fourth cousins have the same great-great-great-grandparents, but not the same great-great-grandparents. And so on.
Removed When the word "removed" is used to describe a relationship, it indicates that the two people are from different generations. The words "once removed" mean that there is a difference of one generation. For example, your mother's first cousin is your first cousin, once removed. This is because your mother's first cousin is one generation younger than your grandparents and you are two generations younger than your grandparents. This one-generation difference equals "once removed." Twice removed means that there is a two-generation difference. You are two generations younger than a first cousin of your grandmother, so you and your grandmother's first cousin are first cousins, twice removed.