, but in modern usage the term is rarely used when referring to a relative in one's own line of descent, or where there is a more specific term to describe the relationship, e.g., brother, sister, aunt, uncle. The term blood relative can be used synonymously, and underlines the existence of a genetic link.

A system of degrees and removes is used to describe the relationship between the two cousins and the ancestor they have in common. The degree (first, second, third cousin, etc.) indicates the minimum number of generations between either cousin and the nearest common ancestor; the remove (once removed, twice removed, etc.) indicates the number of generations, if any, separating the two cousins from each other.

For example, a person with whom you share a grandparent (but not a parent) is a first cousin; someone with whom you share a great-grandparent (but not a grandparent) is a second cousin; and someone with whom you share a great-great-grandparent (but not a great-grandparent) is a third cousin; and so on. The child of your first cousin is your first cousin once removed because the one generation separating you and the child represent one remove. You and the child are still considered first cousins, as your own grandparent (this child's great-grandparent), as the most recent common ancestor, represents one degree.

Non-genealogical usage often eliminates the degrees and removes, and refers to people with common ancestors merely as cousins or distant cousins.

The system can handle kinships going back any number of generations (subject to the genealogical information being available). In 2004, genealogists discovered that U.S. Presidential candidates George W. Bush and John Kerry shared a common ancestral couple in the 1500s. It was reported that the two men are sixteenth cousins, three times removed. However, the two are in fact ninth cousins, twice removed. Also, in 2007, it was revealed that U.S. vice president Dick Cheney and senator Barack Obama are eighth cousins.

If one goes back far enough, at some point all human beings will be found to be related according to the National Center for Biotechnology Information, part of the American National Institutes of Health.

Cousin chart

A cousin chart, or table of consanguinity, is helpful in identifying the degree of cousin relationship between two individuals using their most recent common ancestor as the reference point. Cousinship between two individuals can be specifically described in degrees and removes by determining how close, generationally, the common ancestor is to each individual.

Additional modifying words are used to clarify the exact degree of relatedness between the two people. Ordinal numbers are used to specify the number of generations between individuals and a common ancestor, and further clarification of exact cousinship is made by specifying the difference in generational level between the two cousins, if any, by using degrees of remove. For example, "first cousins once removed" describes two individuals with the common ancestor being the grandparent of one cousin (one degree) and the great-grandparent of the other cousin. The cousins themselves are one generation different from each other (one remove).