What is the term for "cousin of a cousin"?
My mother’s sister’s son is my cousin; let’s call him “John”.
John’s father’s brother’s son — let’s call him Mark — is John’s cousin.
Now, Mark isn’t my direct cousin as we don't share any immediate ancestors. What kind of relationship do I have with Mark? I think this too is some sort of cousin.
I always thought this was second cousin, but it turns out, I have blood relation to a second cousin through great grandparents.
So, what is term for my relationship with Mark?
There isn't any family relationship between you and Mark, except
- the cousin of your cousin is yourself or your sibling
- the cousin of your cousin is also your cousin if his mother is the sister of your father
- the cousin of your cousin is your second cousin if his parents and your parents are cousins (third cousin if the parents are second cousins, and so on)
A term what many people use is grand-cousin. But that's wrong, though it is used ambiguous in colloquial, at least in my mother-tongue. But think of that:
- Your grandparents are the parents of your parent
- Your grandaunt/granduncle is the the aunt/uncle of your parent
This leads to
- Your grand-cousin is the cousin of your parent.
If no blood relation exists there are only few ways how a non-related person can be your cousin: E.g. the person is your step-cousin. But this doesn't work here, because:
Step-cousins are either stepchildren of an individual's aunt or uncle, children of one's step-aunt or uncle, or half-siblings of one's cousin. (WIKIPEDIA)
On the WP page you find a lot of family combinations and what they are called (e.g. Cousin-in-law: spouse of an individual's cousin), but I didn't find the relationship you mention. (Correct me, if I overlooked it)
Conclusion: I would call him cousin of cousin.
As you state, there is no common ancestor, so you are not related.
Colloquially, you can be "cousins" if there is a unique tie, and most readers would understand this. Technically, however, there is no relation.
The technical terms are as follows:
Siblings share the same parents.
Cousins share the same grandparents.
Second cousins share the same great-grandparents.
Third cousins share the same great-great-grandparents,
And so on.
The direct descendants of any cousin are "cousins once removed." thus, the direct child of your second cousins are second cousins once removed.". The grand children of your second cousins is your "second cousins twice removed." and so on.
In-laws refer to relatives related by marriage. As such, I might be tempted to force the construction "cousins-in-law", but it would be a stretch.