I was confused by this once.
Having just read Genesis 24:15 ...behold, Rebekah came out, who was born to Bethuel, son of Milcah, the wife of Nahor, Abraham's brother...
I had to know if there's an English term as to how Rebekah is related to Isaac.
Thanks to a good illustration by this site, this Cousin confusion is clarified for me. One would say, I hit two birds with one stone.
First Cousin are what we usually call cousin.
Second Cousin are called by the children of First Cousins to each other. And Third and so forth.
However, to call the children of my First Cousin, it is called First Cousin, ONCE REMOVED. And the grandchildren of my First Cousin, twice removed, and so forth (three times removed, etc.)
Now since Bethuel is Isaac's First cousin, Rebekah would be Isaac's First Cousin, Once Removed. In addition to being his wife. Thus, the family structure of the ancients.