Your Aunt/Uncle's child.
Your cousin's cousin could either be your cousin or no relation at all.
He is of relation as a cousin-in-law.
Well, your cousin's brother is also your cousin, and a cousin's son is also your cousin.
Your cousin. You are that person's second cousin.
They are your cousin-in-law.
Second cousin
Cousin in Law
Your cousin-in-law.
still your cousin
Your Aunt's first cousin may be your second cousin, onve removed or may be no relation to you at all.
Your Aunt's first cousin may be your second cousin, onve removed or may be no relation to you at all.
There is no relation between you and your grandmother's cousin-in-law's grandson.