The term cousin typically refers to the child of one's parent's sibling. This is more correctly termed a "first cousin". More generally, "cousins" are any relatives that are neither siblings nor direct descendents/ancestors. Ordinal numbers (first, second, third, etc) are used to quantify in which preceding generation the common direct ancestor is located. The term is then completed with a number removed, which indicates how many generations separate the relatives in question.

Thus, if one of John's great-great-grandparents is also one of Mary's great-great-great-great-grandparents, John and Mary are "third cousins twice removed".

The following chart helps to explain the cousin relationships (the term 'Niece' is used to mean 'Niece or Nephew' and is used only for brevity):

Common Ancestor	Parent	Grandparent	Great Grandparent	Great Great Grandparent	Great Great Great Grandparent	Great Great Great Great Grandparent	Great Great Great Great Great Grandparent
Parent	Sibling	Niece	Grandniece	Great Grandniece	Great Great Grandniece	Great Great Great Grandniece	Great Great Great Great Grandniece
Grandparent	Niece	First Cousin	First Cousin Once Removed	First Cousin Twice Removed	First Cousin Thrice Removed	First Cousin Four Times Removed	First Cousin Five Times Removed
Great Grandparent	Grandniece	First Cousin Once Removed	Second Cousin	Second Cousin Once Removed	Second Cousin Twice Removed	Second Cousin Thrice Removed	Second Cousin Four Times Removed
Great Great Grandparent	Great Grandniece	First Cousin Twice Removed	Second Cousin Once Removed	Third Cousin	Third Cousin Once Removed	Third Cousin Twice Removed	Third Cousin Thrice Removed
Great Great Great Grandparent	Great Great Grandniece	First Cousin Thrice Removed	Second Cousin Twice Removed	Third Cousin Once Removed	Fourth Cousin	Fourth Cousin Once Removed	Fourth Cousin Twice Removed
Great Great Great Great Grandparent	Great Great Great Grandniece	First Cousin Four Times Removed	Second Cousin Thrice Removed	Third Cousin Twice Removed	Fourth Cousin Once Removed	Fifth Cousin	Fifth Cousin Once Removed
Great Great Great Great Great Grandparent	Great Great Great Great Grandniece	First Cousin Five Times Removed	Second Cousin Four Times Removed	Third Cousin Thrice Removed	Fourth Cousin Twice Removed	Fifth Cousin Once Removed	Sixth Cousin

© 2000 Rhonda Stolte Darnell