Recently we had as dinner guests a colleague and his wife and during the evening he happened to mention that someone was “his first cousin once removed’. I seized on this because I had never been sure what that meant and so asked him. He said that when he talked about someone being his first cousin once removed, he meant someone who was a child of his first cousin. But when I asked him how that other person would refer to him (since he was not the child of that person’s first cousin) he said he was not sure. I have also heard some people refer to the child of a first cousin as a second cousin.
The invaluable Wikipedia says that there is a logical system. The generic term ‘cousin’ refers to any family relationship where two people share common ancestors without one being an ancestor of the other.
The meanings of the more specific terms are straightforward when two people have the same number of generations to the common ancestors. ‘First cousins’ are the children of siblings. ‘Second cousins’ is how you refer to the children of first cousins (i.e., of the same generation). Third cousins refer to their respective children and so on. In every case, the number of generations separating them from their common ancestors is the same. ‘Cousins once removed’ means that there is a single generation difference between the two people, ‘cousins twice removed’ means that there is a two-generation difference, and so on.
It is quite logical but there still remains the original ambiguity that prompted this post. If you refer to your first cousin’s child as your ‘first cousin once removed’, should that person use the same term to refer to you or say that you are his ‘second cousin once removed’? In other words, is the primary referent number the smaller of the two possibilities or should it be the number of your parallel cousin? In either case, to really pin down the relationship, it seems like we need to specify if the ‘removal’ goes up a generation or down a generation.
This post may have been more helpful if I had done it before the holidays when families and friends get together and introductions require one to describe relationships.